Glucose Infusion Research Articles

1660-P: Lactate Inhibits Lipolysis in Healthy Males—A Randomized Crossover Trial

Background: The intermediary metabolite lactate has signaling capacities through the lactate specific receptor GPR81/HCA1. Ex-vivo, lactate inhibits lipolysis through GPR81, but in-vivo human data are scarce. Lactate-mediated inhibition of lipolysis could improve insulin sensitivity. The aim of the study was to investigate if hyperlactatemia at physiological concentrations inhibits palmitate lipolysis and affects glucose metabolism in healthy males. Methods: In a randomized cross-over design, eight healthy men were studied after an overnight fast on two occasions 1) during a sodium-lactate infusion (LAC) and 2) during a NaCl infusion (CTL). Both study days comprised a 3-hour basal period followed by a 3-hour hyperinsulinemic euglycemic clamp (HEC) period. Lipolysis rate and endogenous glucose production (EGP) were evaluated using [9,10-3H]-palmitate and [3H]-glucose tracers. Average glucose infusion rate (mg/kg/min) during the last 30 min of the HEC (M-value) was used as a measure of insulin sensitivity. Data are mean±SD Results: Plasma lactate increased to 2.6 ±0.6 mmol/L during LAC vs. 0.8 ±0.3 mmol/L during CTL (p<0.001). At the end of the basal period, palmitate flux was 30% lower during LAC compared with CTL (84 ±32 μmol/min vs. 120 ±35 μmol/min, p=0.003). At the end of the HEC, palmitate flux was similarly suppressed during both interventions (p=0.7). Plasma FFA were lower during LAC compared with CTL (0.2 ±0.1 mmol/L vs. 0.3 ±0.1 mmol/L, p=0.03) at the end of the basal period and equally suppressed during both interventions at the end of the HEC (p=0.7). EGP was unaffected by LAC compared with CTL at the end of the basal period (p=1.0) and suppressed at the end of the HEC during both interventions (p=1.0). M-value was unaffected by LAC compared with CTL (p=0.8). Conclusion: Lactate inhibits palmitate lipolysis by 30 %, an effect which per se may improve insulin sensitivity. Hyperlactatemia did not affect EGP or insulin sensitivity, possibly because lactate intrinsically may induce insulin resistance. Disclosure M.G.B.Pedersen: None. N.Rittig: Research Support; ARLA. E.Søndergaard: None. L.C.Gormsen: None. N.Møller: Other Relationship; Aarhus University/Ketlace.

345-OR: Exercise and Liraglutide Synergistically Attenuate Vascular Inflammation and Enhance Metabolic Insulin Action in Diet-Induced Obesity

Endothelial oxidative stress and vascular inflammation induce microvascular insulin resistance which is an early event in diet-induced obesity and contributes to metabolic insulin resistance. To examine whether exercise and glucagon-like peptide 1 (GLP-1) receptor agonism, alone or in combination, modulate vascular and metabolic insulin actions during obesity development, we performed an euglycemic insulin clamp, in conjunction with contrast enhanced ultrasound, in adult male rats after 2 weeks of high-fat diet feeding with either access to running wheel (exercise), liraglutide (200 mg/kg subcutaneously twice daily), or the combination of both. Rats exhibited increased visceral adiposity and blunted microvascular responses (microvascular blood volume, flow velocity, and total flow) and metabolic insulin actions (glucose infusion rates). Exercise and liraglutide alone each improved muscle insulin sensitivity but their combination fully restored insulin-mediated glucose infusion rates. The combined exercise and liraglutide intervention enhanced insulin-mediated muscle microvascular perfusion, reduced perivascular macrophage accumulation and oxidative stress in the muscle, attenuated blood vessel inflammation and improved endothelial function, along with increased nucleus translocation of nuclear factor erythroid 2-related factor 2 (NRF2) and phosphorylation of AMP-activated protein kinase (AMPK) and nitric oxide synthase (eNOS) in endothelial cells. We conclude that exercise and liraglutide synergistically enhance the metabolic actions of insulin and reduce vascular oxidative stress and inflammation in the early stage of obesity development. Our data suggest that early combination use of exercise and GLP-1 receptor agonism might be an effective strategy in preventing microvascular and metabolic insulin resistance and associated complications during the development of obesity. Disclosure J.Liu: None. K.W.Aylor: None. Z.Liu: None. Funding National Institutes of Health (R01DK125330), (R01DK1124344 to Z.L.)

1514-P: Insulin Sensitivity Initially Worsens but Later Improves with Aging in C57BL/6N Mice

Objective: Aging is believed to induce insulin resistance in humans. However, when and how insulin sensitivity changes with aging remain unclear in both humans and mice. Methods: Groups of C57BL/6N mice at 9-15 weeks (young), 34-67 weeks (one-year-old) and 107-121 weeks (two-year-old) of age underwent hyperinsulinemic-euglycemic clamp studies with somatostatin infusion under awake and non-restrained conditions. Results: The glucose infusion rates for maintaining euglycemia were 17.11±2.94, 5.58±1.28 and 25.30±4.42 mg/kg/min in young, one-year-old and two-year-old mice, respectively. Thus, compared with young mice, one-year-old mice exhibited the expected insulin resistance. In contrast, the insulin sensitivity of two-year-old mice showed significant improvement. These age-related changes were mainly observed in glucose uptake into adipose tissue and skeletal muscle. Epididymal fat weight and hepatic triglyceride levels were highest in one-year-old mice, while being similar in young and two-year-old mice. Conclusions: Our observations indicate that, in mice, insulin resistance appears at one year of age but subsequently improves markedly. These alterations in insulin sensitivity are attributable to changes in visceral fat accumulations and age-related factors. Disclosure H.Kondo: None. H.Ono: None. K.Yokote: None. Funding Japan Society for the Promotion of Science (15K09398, 18K08502, 20H00524); Japan Agency for Medical Research and Development (17GM5010002H0001, 18GM5010002H0002, 19GM5010002H0003, 20GM5010002H0004)

293-OR: Macrophage-Derived Interleukin-12 Regulates Obesity-Mediated Insulin Resistance in the Liver

Inflammation and insulin resistance play a major role in nonalcoholic fatty liver disease (NAFLD), and IL-12, a pro-inflammatory cytokine primarily secreted by macrophages, is elevated in obesity. Here, we examined the effects of acute treatment with IL-12 in vivo on glucose metabolism in male C57BL/6J mice. Mouse recombinant IL-12 (0.25 μg/hour) or saline (control) was infused for 4 hours, followed by insulin clamps in mice (n=5/group). Glucose infusion rates during clamps were significantly reduced in IL-12-treated mice, resulting in a 34% decrease compared to controls (Fig. 1-2). Basal hepatic glucose production (HGP) did not differ, but clamp HGP was significantly increased in IL-12-treated mice (Fig. 3). As a result, IL-12 treatment caused a 43% decrease in hepatic insulin action compared to controls (Fig. 4). These IL-12 effects were associated with a 4-fold increase in STAT4 tyrosine-phosphorylation (0.071±0.026 vs. 0.018±0.004 in controls) and a 47% decrease in IRS1 protein levels (0.264±0.044 vs. 0.496±0.112 in controls) in the liver. Attenuated liver IL-12 level was further associated with improved hepatic insulin action in diet-induced obese mice with conditional loss of IFNγ signaling in myeloid cells. CONCLUSION: Our findings identify IL-12 as a novel cytokine regulating obesity-mediated insulin resistance and inflammation in the liver and a potential therapeutic target to treat NAFLD. Disclosure R.H.Friedline: None. M.Albusharif: None. A.M.Kim: None. L.H.Kim: None. N.M.Baez torres: None. L.A.Tauer: None. X.Hu: None. J.K.Kim: None. Funding National Institutes of Health (5U2CDK093000)

191-OR: Deletion of the Type 2 Diabetes Candidate Gene SLC16A11 Reduces Peripheral Insulin Sensitivity in Mice

Background and Aims: Recent GWAS in large human populations identified the monocarboxylate transporter SLC16A11 as a candidate gene for T2D. While previous studies postulated that SLC16A11 plays a role in hepatic lipid and glucose metabolism, the existing data are controversial and exact mechanisms of how SLC16A11 affects T2D are missing. Here, we aimed at elucidating the role of SLC16A11 in the development of metabolic disease. Methods: HEK293 cell lines expressing murine and human SLC16A11 were established. Moreover, using CRISPR/Cas9, a SLC16A11 knockout mouse model was generated. Finally, SLC16A11 mRNA expression was measured in various insulin responsive tissues of ob/ob and db/db mice. Results: In HEK293 cells, substrates of the transporter were identified. mRNA expression of SLC16A11 was reduced in skeletal muscle of ob/ob and db/db mice (-69.8% and -22.8%; p<0.05) compared to littermate controls. SLC16A11 KO and WT littermate mice fed NCD or HFD did not differ in body weight and composition, energy expenditure or food intake. While basal glucose and insulin in SLC16A11 KO and WT littermates on a HFD were not different, glucose infusion rate during hyperinsulinemic euglycemic clamp was lower in SLC16A11 KO mice (SLC16A11 WT= 36.4±3 mg/kg/min; SLC16A11 KO= 24.7±2 mg/kg/min; P<0.01), indicating reduced whole-body insulin sensitivity. No changes were observed in hepatic glucose production, liver fat content or hepatic mitochondrial function using PINTA method. Instead, clamped 2-deoxy-glucose uptake was significantly reduced in skeletal muscle (-41%; p<0.05) of SLC16A11 KO, together with increased DAGs levels and PKCθ activation, indicating skeletal muscle insulin resistance. Conclusions: Our data show for the first time that in contrast to previous assumptions, SLC16A11 impairs skeletal muscle insulin sensitivity without affecting hepatic metabolism. Taking also human GWAS into account, we propose that SLC16A11 may be an interesting target for the treatment of T2D. Disclosure N.N.El-agroudy: None. T.Schumann: None. A.Kurzbach: None. G.Sancar: None. L.Sandforth: None. C.Herrmann: None. G.I.Shulman: Consultant; Novo Nordisk, DiCerna Pharmaceuticals, Inc., Bayer Consumer Care AG, Kriya Therapeutics, Arrowhead Pharmaceuticals, Inc., ESPERION Therapeutics, Inc., Other Relationship; AstraZeneca, Merck & Co., Inc., Janssen Research & Development, LLC, iMetabolic Biopharma Corporation, Maze Therapeutics, 89bio, Inc., Equator Therapeutics, Inc., Generian Pharmaceuticals, Fortress Biotech, Inc., OrsoBio, Aro Biotherapeutics Company, Stock/Shareholder; Levels Health, Inc. A.L.Birkenfeld: None.

1559-P: Glucagon Receptor–Mediated Improvements in Glycemia Are Dependent on Agonist Pharmacodynamics

Glucagon is considered the main glucose counter-regulatory hormone to insulin. Although, chronic glucagon receptor (GCGR) agonism induces hyperglycemia and glucose intolerance, it also improves insulin secretion and action. Surprisingly, we found chronic treatment with the selective, long-acting GCGR agonist, IUB288, improves ad libitum glycemia and glucose tolerance 4h after treatment. These glycemic improvements were associated with enhanced AKT phosphorylation, despite control-like insulin levels. We next tested if these results could be replicated with a short acting GCGR agonist. IUB94 displays improved aqueous solubility but maintains the short half-life and potency of native glucagon. 4h glucose excursion was monitored in lean mice after injection of IUB288, IUB94, or vehicle. We observed a transient rise in blood glucose (BG) 15min after either IUB288 or IUB94 compared to vehicle. Intriguingly, IUB288-treated mice exhibited improved BG from 120-240min, while BG in IUB94-treated mice was similar to vehicle controls. These data suggest that acute BG regulation is agonist-dependent yet, it remains unclear if pharmacodynamics or some inherent difference in potency is influencing the 4h BG. We next treated lean mice for 4d with vehicle or IUB288, measuring ad libitum glycemia over the final 24h period. IUB288-treated mice displayed improved glycemia 4h after the last injection and hyperglycemia after 12h, compared to vehicle-treated controls, suggesting chronic GCGR agonism is not exclusively hyperglycemic. Surprisingly, 4d IUB288 treatment in diet-induced obese (DIO) mice reduced ad libitum glycemia for a longer duration than observed in chow IUB288-treated mice. IUB288 treatment also increased glucose infusion rate, suppression of endogenous glucose production, and AKT phosphorylation during hyperinsulinemic-euglycemic clamps. These data provide insight into the potential therapeutic use of sustained-acting GCGR agonists against diabetes and obesity. Disclosure S.Nason: None. T.Kim: None. J.Antipenko: None. B.Yang: None. R.Dimarchi: None. K.M.Habegger: Consultant; Glyscend Inc., Research Support; Eli Lilly and Company, Novo Nordisk, Glyscend Inc., Stock/Shareholder; Glyscend Inc. Funding National Institutes of Health

1554-P: Carnosic Acid Protects against Short-Term Lipid-Infusion–Induced Glucose Intolerance in Mice

Background: Obesity and type 2 diabetes (T2D) are associated with elevated plasma free fatty acids (FFA). In vivo exposure to FFAs, such as palmitate, by lipid infusion results in insulin resistance as observed in obesity and T2D. In recent years, compounds found in herbs and plants have attracted attention for prevention and treatment of insulin resistance and T2D. In recent studies by our group, carnosic acid (CA), found in rosemary, increased glucose uptake and attenuated the FFA (palmitate)-induced insulin resistance in muscle cells and adipocytes. In addition, CA caused a robust activation of AMP-activated protein kinase (AMPK). Our present study aimed to examine the effects of CA in short-term FFA-induced glucose intolerance in mice. Material and Methods: C57Bl/6J mice were cannulated in their jugular veins and infused for 48h with ethylpalmitate (EtP, nontoxic method of elevating circulating palmitate because of hydrolysis to palmitate and ethanol by plasma esterases), mimicking elevated FFA levels seen in obesity. In addition, a group of mice were infused with EtP plus 50 mg/kg CA for 48h. Ethanol vehicle with or without CA were two additional control groups. At the end of the infusions, the mice were subjected to a 2 hr hyperglycemic clamp (20 mM glucose) and the glucose infusion rate was measured to assess glucose tolerance. Results: Preliminary data revealed that mice infused with EtP and CA had a higher glucose infusion rate (GIR; mg/kg*min) (66.5±10, mean±SEM) than mice infused with EtP alone (22.7±10). The EtP and CA was comparable to the GIR of ethanol vehicle infused mice (73±9). Future Directions: Further analysis of collected plasma and tissue will be used to assess insulin resistance and beta cell function in vivo and to elucidate the mechanisms of CA alleviation of FFA-induced insulin resistance. Conclusions: Our data indicate that CA has the potential to counteract FFA-induced glucose intolerance in mice. Disclosure N.Tsakiridis: None. F.Vlavcheski: None. E.Tsiani: None. A.Giacca: None.

Cerebral Glucose Concentration in Neonatal Hypoxic–Ischemic Encephalopathy during Therapeutic Hypothermia

To determine cerebral glucose concentration and its relationship with glucose infusion rate (GIR) and blood glucose concentration in neonatal encephalopathy during therapeutic hypothermia (TH). This was an observational study in which cerebral glucose during TH was quantified by magnetic resonance (MR) spectroscopy and compared with mean blood glucose at the time of scan. Clinical data (gestational age, birth weight, GIR, sedative use) that could affect glucose use were collected. The severity and pattern of brain injury on MR imaging were scored by a neuroradiologist. Student t test, Pearson correlation, repeated measures ANOVA, and multiple regression analysis were performed. Three-hundred-sixty blood glucose values and 402MR spectra from 54 infants (30 female infants; mean gestational age 38.6± 1.9weeks) were analyzed. In total, 41 infants had normal-mild and 13 had moderate-severe injury. Median GIR and blood glucose during TH were 6.0mg/kg/min (IQR 5-7) and 90mg/dL (IQR 80-102), respectively. GIR did not correlate with blood or cerebral glucose. Cerebral glucose was significantly greater during than after TH (65.9± 22.9 vs 60.0± 25.2mg/dL, P<.01), and there was a significant correlation between blood glucose and cerebral glucose during TH (basal ganglia: r=0.42, thalamus: r=0.42, cortical gray matter: r=0.39, white matter: r=0.39, all P<.01). There was no significant difference in cerebral glucose concentration in relation to injury severity or pattern. During TH, cerebral glucose concentration is partly dependent on blood glucose concentration. Further studies to understand brain glucose use and optimal glucose concentrations during hypothermic neuroprotection are needed.

Hypoglycaemia frequency and physiological response after double or triple doses of once-weekly insulin icodec vs once-daily insulin glargine U100 in type 2 diabetes: a randomised crossover trial

Aims/hypothesisThis study compared the frequency of hypoglycaemia, time to hypoglycaemia and recovery from hypoglycaemia after double or triple doses of once-weekly insulin icodec vs once-daily insulin glargine U100. Furthermore, the symptomatic and counterregulatory responses to hypoglycaemia were compared between icodec and glargine U100 treatment.MethodsIn a randomised, single-centre (Department of Internal Medicine, Division of Endocrinology and Diabetology, Medical University of Graz, Graz, Austria), open-label, two-period crossover trial, individuals with type 2 diabetes (age 18–72 years, BMI 18.5–37.9 kg/m2, HbA1c ≤75 mmol/mol [≤9.0%]) treated with basal insulin with or without oral glucose-lowering drugs received once-weekly icodec (for 6 weeks) and once-daily glargine U100 (for 11 days). Total weekly doses were equimolar based on individual titration of daily glargine U100 during the run-in period (target fasting plasma glucose [PG]: 4.4–7.2 mmol/l). Randomisation was carried out by assigning a randomisation number to each participant in ascending order, which encoded to one of two treatment sequences via a randomisation list prepared prior to the start of the trial. At steady state, double and triple doses of icodec and glargine U100 were administered followed by hypoglycaemia induction: first, euglycaemia was maintained at 5.5 mmol/l by variable i.v. infusion of glucose; glucose infusion was then terminated, allowing PG to decrease to no less than 2.5 mmol/l (target PGnadir). The PGnadir was maintained for 15 min. Euglycaemia was restored by constant i.v. glucose (5.5 mg kg−1 min−1). Hypoglycaemic symptoms score (HSS), counterregulatory hormones, vital signs and cognitive function were assessed at predefined PG levels towards the PGnadir.ResultsHypoglycaemia induction was initiated in 43 and 42 participants after double dose of icodec and glargine U100, respectively, and in 38 and 40 participants after triple doses, respectively. Clinically significant hypoglycaemia, defined as PGnadir <3.0 mmol/l, occurred in comparable proportions of individuals treated with icodec vs glargine U100 after double (17 [39.5%] vs 15 [35.7%]; p=0.63) and triple (20 [52.6%] vs 28 [70.0%]; p=0.14) doses. No statistically significant treatment differences were observed in the time to decline from PG values of 5.5 mmol/l to 3.0 mmol/l (2.9–4.5 h after double dose and 2.2–2.4 h after triple dose of the insulin products). The proportion of participants with PGnadir ≤2.5 mmol/l was comparable between treatments after double dose (2 [4.7%] for icodec vs 3 [7.1%] for glargine U100; p=0.63) but higher for glargine U100 after triple dose (1 [2.6%] vs 10 [25.0%]; p=0.03). Recovery from hypoglycaemia by constant i.v. glucose infusion took <30 min for all treatments. Analyses of the physiological response to hypoglycaemia only included data from participants with PGnadir <3.0 mmol/l and/or the presence of hypoglycaemic symptoms; in total 20 (46.5%) and 19 (45.2%) individuals were included after a double dose of icodec and glargine U100, respectively, and 20 (52.6%) and 29 (72.5%) individuals were included after a triple dose of icodec and glargine U100, respectively. All counterregulatory hormones (glucagon, adrenaline [epinephrine], noradrenaline [norepinephrine], cortisol and growth hormone) increased during hypoglycaemia induction with both insulin products at both doses. Following triple doses, the hormone response was greater with icodec vs glargine U100 for adrenaline at PG3.0 mmol/l (treatment ratio 2.54 [95% CI 1.69, 3.82]; p<0.001), and cortisol at PG3.0 mmol/l (treatment ratio 1.64 [95% CI 1.13, 2.38]; p=0.01) and PGnadir (treatment ratio 1.80 [95% CI 1.09, 2.97]; p=0.02). There were no statistically significant treatment differences in the HSS, vital signs and cognitive function.Conclusions/interpretationDouble or triple doses of once-weekly icodec lead to a similar risk of hypoglycaemia compared with double or triple doses of once-daily glargine U100. During hypoglycaemia, comparable symptomatic and moderately greater endocrine responses are elicited by icodec vs glargine U100.Trial registrationClinicalTrials.gov NCT03945656.FundingThis study was funded by Novo Nordisk A/S.Graphical

Effects of acute changes in fasting glucose and free fatty acid concentrations on indices of β-cell function and glucose metabolism in subjects without diabetes.

Elevated fasting free fatty acids (FFAs) and fasting glucose are additively associated with impaired glucose tolerance (IGT) and decreased β-cell function [quantified as disposition index (DI)]. We sought to examine how changes in fasting FFA and glucose alter islet function. We studied 10 subjects with normal fasting glucose (NFG) and normal glucose tolerance (NGT) on two occasions. On one occasion, Intralipid and glucose were infused overnight to mimic conditions present in IFG/IGT. In addition, we studied seven subjects with IFG/IGT on two occasions. On one occasion, insulin was infused to lower overnight FFA and glucose concentrations to those observed in people with NFG/NGT. The following morning, a labeled mixed meal was used to measure postprandial glucose metabolism and β-cell function. Elevation of overnight fasting FFA and glucose in NFG/NGT did not alter peak or integrated glucose concentrations (2.0 ± 0.1 vs. 2.0 ± 0.1 Mol per 5 h, Saline vs. Intralipid/glucose, P = 0.55). Although overall β-cell function quantified by the Disposition Index was unchanged, the dynamic component of β-cell responsivity (ϕd) was decreased by Intralipid and glucose infusion (9 ± 1 vs. 16 ± 3 10-9, P = 0.02). In people with IFG/IGT, insulin did not alter postprandial glucose concentrations or indices of β-cell function. Endogenous glucose production and glucose disappearance were also unchanged in both groups. We conclude that acute, overnight changes in FFA, and glucose concentrations do not alter islet function or glucose metabolism in prediabetes.NEW & NOTEWORTHY This experiment studied the effect of changes in overnight concentrations of free fatty acids (FFAs) and glucose on β-cell function and glucose metabolism. In response to elevation of these metabolites, the dynamic component of the β-cell response to glucose was impaired. This suggests that in health overnight hyperglycemia and FFA elevation can deplete preformed insulin granules in the β-cell.

Insulin sensitivity initially worsens but later improves with aging in male C57BL/6N mice.

Aging is believed to induce insulin resistance in humans. However, when and how insulin sensitivity changes with aging remain unclear in both humans and mice. In this study, groups of male C57BL/6N mice at 9-19 weeks (young), 34-67 weeks (mature adult), 84-85 weeks (presenile) and 107-121 weeks (aged) of age underwent hyperinsulinemic-euglycemic clamp studies with somatostatin infusion under awake and non-restrained conditions. The glucose infusion rates for maintaining euglycemia were 18.4±2.9, 5.9±1.3, 20.3±7.2 and 25.3±4.4mg/kg/min in young, mature adult, presenile and aged mice, respectively. Thus, compared with young mice, mature adult mice exhibited the expected insulin resistance. In contrast, presenile and aged mice showed significantly higher insulin sensitivity than the mature adult mice. These age-related changes were mainly observed in glucose uptake into adipose tissue and skeletal muscle (rates of glucose disappearance were 24.3±2.0, 17.1±1.0, 25.5±5.2 and 31.8±2.9mg/kg/min in young, mature adult, presenile and aged mice, respectively). Epididymal fat weight and hepatic triglyceride levels were higher in mature adult mice than those in young and aged mice. Our observations indicate that, in male C57BL/6N mice, insulin resistance appears at the mature adult stage of life but subsequently improves markedly. These alterations in insulin sensitivity are attributable to changes in visceral fat accumulations and age-related factors.

Retained Metabolic Flexibility of the Failing Human Heart.

The failing heart is traditionally described as metabolically inflexible and oxygen starved, causing energetic deficit and contractile dysfunction. Current metabolic modulator therapies aim to increase glucose oxidation to increase oxygen efficiency of adenosine triphosphate production, with mixed results. To investigate metabolic flexibility and oxygen delivery in the failing heart, 20 patients with nonischemic heart failure with reduced ejection fraction (left ventricular ejection fraction 34.9±9.1) underwent separate infusions of insulin+glucose infusion (I+G) or Intralipid infusion. We used cardiovascular magnetic resonance to assess cardiac function and measured energetics using phosphorus-31 magnetic resonance spectroscopy. To investigate the effects of these infusions on cardiac substrate use, function, and myocardial oxygen uptake (MVo2), invasive arteriovenous sampling and pressure-volume loops were performed (n=9). At rest, we found that the heart had considerable metabolic flexibility. During I+G, cardiac glucose uptake and oxidation were predominant (70±14% total energy substrate for adenosine triphosphate production versus 17±16% for Intralipid; P=0.002); however, no change in cardiac function was seen relative to basal conditions. In contrast, during Intralipid infusion, cardiac long-chain fatty acid (LCFA) delivery, uptake, LCFA acylcarnitine production, and fatty acid oxidation were all increased (LCFA 73±17% of total substrate versus 19±26% total during I+G; P=0.009). Myocardial energetics were better with Intralipid compared with I+G (phosphocreatine/adenosine triphosphate 1.86±0.25 versus 2.01±0.33; P=0.02), and systolic and diastolic function were improved (LVEF 34.9±9.1 baseline, 33.7±8.2 I+G, 39.9±9.3 Intralipid; P<0.001). During increased cardiac workload, LCFA uptake and oxidation were again increased during both infusions. There was no evidence of systolic dysfunction or lactate efflux at 65% maximal heart rate, suggesting that a metabolic switch to fat did not cause clinically meaningful ischemic metabolism. Our findings show that even in nonischemic heart failure with reduced ejection fraction with severely impaired systolic function, significant cardiac metabolic flexibility is retained, including the ability to alter substrate use to match both arterial supply and changes in workload. Increasing LCFA uptake and oxidation is associated with improved myocardial energetics and contractility. Together, these findings challenge aspects of the rationale underlying existing metabolic therapies for heart failure and suggest that strategies promoting fatty acid oxidation may form the basis for future therapies.

Continuous subcutaneous insulin infusion via an insulin pump in extremely premature neonates—a case series

Extremely preterm infants are prone to hyperglycemia which is associated with increased mortality and morbidity. Insulin sensitivity is variable in extreme prematurity, and its monitoring, prevention, and treatment are a significant challenge in the NICU. Frequent changes in fluid composition and volumes, as well as large growth and adaptational nutrient requirements are limited by difficult vascular access and blood sampling and risk of drug incompatibilities. Insulin treatment requires specific access and significantly increases fluid intake and sampling. Clinicians, therefore, often compromise by reducing glucose intake and accepting higher glycemia. We report a case series of 11 extremely low birth weight (ELBW) preterms, born between 23 5/7 and 27 6/7 weeks of gestation, treated for transient hyperglycemia during the first 2 weeks of life by continuous subcutaneous insulin infusion (CSII). Insulin concentration was 10 IU/ml, administered via 13 mm Accu-Chek® Tenderlink catheters and a commercial insulin pump (Accu-Chek® Combo, Roche Diabetes Care). Insulin treatment was initiated when glycemia was > 252 mg/dL (14 mmol/l) in two consecutive blood glucose determinations, except for one case when glycemia was 234 mg/dL (13 mmol/l), despite a previous decrease in glucose infusion rate. The starting dose for the CSII was between 0.01 and 0.08 IU/kg/h. The average duration of the CSII was 5 days (1–16 days). CSII in extreme preterm neonates with hyperglycemia was clinically feasible and practical by sparing IV lines and volume and appeared as more rapidly effective than continuous IV administration. No adverse events like hypoglycemia or skin infection were recorded.

Bioequivalence and immunogenicity of insulin LisPro biosimilar compared to reference drug

Introduction. Insulin therapy is the only treatment for type 1 DM and one of the options for intensifying the treatment for type 2 DM. The production of own insulin biosimilars will increase patients access to the providing drugs and can potentially reduce medical costs on healthcare for government. Aim. Compare the equivalence of pharmacokinetics (PK) and pharmacodynamics (PD), safety, efficacy, and immunogenicity between insulin biosimilar RinLis®, 100 IU/ml (LLC GEROPHARM, Russia) to original Humalog®, 100 IU/ml (Lilly France, France). Materials and methods. The clinical trial was conducted in two phases. Phase I – randomized double-blind, two-arm crossover study of PK and PD using hyperinsulinemic euglycemic clamp (HEC) method in 28 healthy volunteers (NCT03604575). During HEC regular blood sampling was performed to assess glucose and insulin concentrations. The glucose infusion rate (GIR) was adjusted based on glycemia measurement. These data were used to calculate the PD parameters: the total area under the GIR-time curve (AUCGIR) and the maximum GIR over the observation period (GIRmax); PK parameters: the total area under the concentration – time curve (AUCins.) and the maximum insulin concentration over the HEC (Сins. max). Phase II – randomized multicenter open-label comparative study in parallel groups with an assessment the frequency of an immune response after 26 weeks of therapy (NCT04023344). The comparability of the studied drugs was considered proven if 90% confidence intervals (CI) for the ratio of geometric means of FC and PD were in the range of 80–125%. Results. In the course of the study, it was revealed that RinLiz® and Humalog® insulin had comparable PK and PD profiles. The ratio of the geometric mean values of the AUCGIR and GIRmax were in the range of 80–125% and amounted to 106 [95–118] % and 108 [97–121] %, respectively. The equivalence also was confirmed by the ratio of the geometric mean values of the AUCins. and Сins. max, which amounted to 91 [86–97] % and 94 [91–97] %. In the second phase of the study after 26 weeks of therapy the frequency of immune response between two groups did not differ. Conclusion. The obtained data have demonstrated the bioequivalence and immunogenicity of RinLiz® insulin to the original Humalog® in terms of PK, PD and safety parameters.

Effects of subtotal pancreatectomy and long-term glucose and lipid overload on insulin secretion and glucose homeostasis in minipigs.

Nowadays, there are no strong diabetic pig models, yet they are required for various types of diabetes research. Using cutting-edge techniques, we attempted to develop a type 2 diabetic minipig model in this study by combining a partial pancreatectomy (Px) with an energetic overload administered either orally or parenterally. Different groups of minipigs, including Göttingen-like (GL, n = 17) and Ossabaw (O, n = 4), were developed. Prior to and following each intervention, metabolic assessments were conducted. First, the metabolic responses of the Göttingen-like (n = 3) and Ossabaw (n = 4) strains to a 2-month High-Fat, High-Sucrose diet (HFHSD) were compared. Then, other groups of GL minipigs were established: with a single Px (n = 10), a Px combined with a 2-month HFHSD (n = 6), and long-term intraportal glucose and lipid infusions that were either preceded by a Px (n = 4) or not (n = 4). After the 2-month HFHSD, there was no discernible change between the GL and O minipigs. The pancreatectomized group in GL minipigs showed a significantly lower Acute Insulin Response (AIR) (18.3 ± 10.0 IU/mL after Px vs. 34.9 ± 13.7 IU/mL before, p < .0005). In both long-term intraportal infusion groups, an increase in the Insulinogenic (IGI) and Hepatic Insulin Resistance Indexes (HIRI) was found with a decrease in the AIR, especially in the pancreatectomized group (IGI: 4.2 ± 1.9 after vs. 1.5 ± 0.8 before, p < .05; HIRI (×10-5 ): 12.6 ± 7.9 after vs. 3.8 ± 4.3 before, p < .05; AIR: 24.4 ± 13.7 µIU/mL after vs. 43.9 ± 14.5 µIU/mL before, p < .005). Regardless of the group, there was no fasting hyperglycemia. In this study, we used pancreatectomy followed by long-term intraportal glucose and lipid infusions to develop an original minipig model with metabolic syndrome and early signs of glucose intolerance. We reaffirm the pig's usefulness as a preclinical model for the metabolic syndrome but without the fasting hyperglycemia that characterizes diabetes mellitus.

Role for insulin sensitivity in the cerebrovascular response to hyperinsulinemia in young adults

Objective: Cerebral blood flow is highly regulated and cerebrovascular responsiveness to vasodilatory stimuli is predictive of brain health. In preclinical animal models, insulin elicits cerebrovascular dilation and subsequent increases in cerebral blood flow. Contrary to this, preliminary data from our group in a large cohort of healthy humans indicate surrogate measures of cerebral blood flow remain at baseline levels during hyperinsulinemia – although responses were highly variable. In the peripheral circulation, insulin-stimulated vasodilation is closely associated with markers of insulin sensitivity (e.g., elevated fasting glucose, insulin, HOMA-IR); whether these associations translate to the cerebral circulation remains unclear. With this information in mind, we hypothesized the degree of insulin-mediated increases in cerebral blood flow would correlate with indices of peripheral insulin sensitivity.Methods: Middle cerebral artery blood velocity (MCAv) was measured with transcranial Doppler ultrasound in 17 adults (11M/6F, 28±2 yrs, 24±1 kg/m 2 ) at baseline and following a 60-min hyperinsulinemic (40 mU/m 2 body surface area/min), euglycemic infusion. Correlations between MCAv and indices of peripheral insulin sensitivity [i.e., fasting glucose, insulin, HOMA-IR, glucose infusion rate, weight, body mass index (BMI), age, physical activity] were determined. Results: Intravenous insulin infusion increased plasma insulin concentrations (6±1 to 49±3 μIU/mL, p&lt;0.001) with blood glucose maintained (73±4 to 82±6 mg/dL, p=0.196). There was no net change in MCAv during hyperinsulinemia (60±4 to 60±4 cm/s, p=0.930). We observed negative associations between the change in MCAv during hyperinsulinemia (Δ=Insulin–Baseline) and both body weight (R=-0.49, p=0.047) and BMI (R=-0.50, p=0.040). No correlations between ΔMCAv and fasting glucose (p=0.435), insulin (p=0.733), HOMA-IR (p=0.960), age (p=0.132), physical activity (p=0.179), or glucose infusion rate (p=0.599) were observed. Conclusions: As previously shown in these participants, hyperinsulinemia in young adults elicits no net change in MCAv. Any increases in MCAv during hyperinsulinemia occur primarily in individuals with lower body weight and lower BMI. Future studies are needed to translate results to disease states (e.g., diabetes). Margaret W. Mangel Faculty Research Catalyst Fund (JP, JKL), NIH HL137769 (JP), NIH HL130339 (JKL) This is the full abstract presented at the American Physiology Summit 2023 meeting and is only available in HTML format. There are no additional versions or additional content available for this abstract. Physiology was not involved in the peer review process.

Impact of ergot alkaloid and steroidal implant on whole-body protein turnover and expression of mTOR pathway proteins in muscle of cattle.

Holstein steers (n = 32) were used to determine if the ergot analog, bromocriptine decreases muscle protein synthesis through inhibitory action on the mTOR pathway via a direct effect on signal proteins, and if these negative effects can be alleviated with anabolic agents. Steers were treated with intramuscular administration of bromocriptine (vehicle or 0.1 mg/kg BW) and a subdermal commercial steroidal implant containing trenbolone acetate (TBA) and estradiol 17β (with or without), in a 2×2 factorial design. During the 35 day experiment, intake was restricted to 1.5 times maintenance energy requirement. On days 27 through 32, steers were moved to metabolism stalls for urine collection, and whole-body protein turnover was determined using a single pulse dose of [15N] glycine into the jugular vein on day 28. On day 35, skeletal muscle samples were collected before (basal state) and 60 min after (stimulated state) an i.v. glucose challenge (0.25 g glucose/kg). Blood samples were collected at regular intervals before and after glucose infusion for determination of circulating concentrations of glucose and insulin. Bromocriptine reduced insulin and glucose clearance following the glucose challenge, indicating decreased insulin sensitivity and possible disruption of glucose uptake and metabolism in the skeletal muscle. Conversely, analysis of whole-body protein turnover demonstrated that bromocriptine does not appear to affect protein synthesis or urea excretion. Western immunoblot analysis of skeletal muscle showed that it did not affect abundance of S6K1 or 4E-BP1, so bromocriptine does not appear to inhibit activation of the mTOR pathway or protein synthesis. Estradiol/TBA implant decreased urea excretion and protein turnover but had no effect on protein synthesis, suggesting that steroidal implants promote protein accretion through unchanged rates of synthesis and decreased degradation, even in the presence of bromocriptine, resulting in improved daily gains. Implanted steers likely experienced increased IGF-1 signaling, but downstream activation of mTOR, S6K and 4E-BP1, and thus increased protein synthesis did not occur as expected. Overall, this data suggests that bromocriptine does not have a negative impact on muscle protein synthetic pathways independent of DMI.

Hypothalamic Reactivity and Connectivity following Intravenous Glucose Administration.

Dysfunctional glucose sensing in homeostatic brain regions such as the hypothalamus is interlinked with the pathogenesis of obesity and type 2 diabetes mellitus. However, the physiology and pathophysiology of glucose sensing and neuronal homeostatic regulation remain insufficiently understood. To provide a better understanding of glucose signaling to the brain, we assessed the responsivity of the hypothalamus (i.e., the core region of homeostatic control) and its interaction with mesocorticolimbic brain regions in 31 normal-weight, healthy participants. We employed a single-blind, randomized, crossover design of the intravenous infusion of glucose and saline during fMRI. This approach allows to investigate glucose signaling independent of digestive processes. Hypothalamic reactivity and connectivity were assessed using a pseudo-pharmacological design and a glycemia-dependent functional connectivity analysis, respectively. In line with previous studies, we observed a hypothalamic response to glucose infusion which was negatively related to fasting insulin levels. The observed effect size was smaller than in previous studies employing oral or intragastric administration of glucose, demonstrating the important role of the digestive process in homeostatic signaling. Finally, we were able to observe hypothalamic connectivity with reward-related brain regions. Given the small amount of glucose employed, this points toward a high responsiveness of these regions to even a small energy stimulus in healthy individuals. Our study highlights the intricate relationship between homeostatic and reward-related systems and their pronounced sensitivity to subtle changes in glycemia.

Intra-arterial verapamil improves functional outcomes of thrombectomy in a preclinical model of extended hyperglycemic stroke.

The abrupt hyperglycemic reperfusion following thrombectomy has been shown to harm the efficacy of the intervention in stroke patients with large vessel occlusion. Studies of ours and others have shown thioredoxin-interacting protein (TXNIP) is critically involved in hyperglycemic stroke injury. We recently found verapamil ameliorates cerebrovascular toxicity of tissue plasminogen activators in hyperglycemic stroke. The present study aims to answer if verapamil exerts direct neuroprotective effects and alleviates glucose toxicity following thrombectomy in a preclinical model of hyperglycemic stroke. Primary cortical neural (PCN) cultures were exposed to hyperglycemic reperfusion following oxygen-glucose deprivation (OGD), with or without verapamil treatment. In a mouse model of intraluminal stroke, animals were subjected to 4h middle cerebral artery occlusion (MCAO) and intravenous glucose infusion. Glucose infusion lasted one more hour at reperfusion, along with intra-arterial (i.a.) verapamil infusion. Animals were subjected to sensorimotor function tests and histological analysis of microglial phenotype at 72h post-stroke. According to our findings, glucose concentrations (2.5-20mM) directly correlated with TXNIP expression in OGD-exposed PCN cultures. Verapamil (100nM) effectively improved PCN cell neurite growth and reduced TXNIP expression as well as interaction with NOD-like receptor pyrin domain-containing-3 (NLRP3) inflammasome, as determined by immunoblotting and immunoprecipitation. In our mouse model of extended hyperglycemic MCAO, i.a. verapamil (0.5mg/kg) could attenuate neurological deficits induced by hyperglycemic stroke. This was associated with reduced microglial pro-inflammatory transition. This finding encourages pertinent studies in hyperglycemic patients undergoing thrombectomy where the robust reperfusion may exacerbate glucose toxicity.

Case report - sulfonylurea poisoning mimicking vertebrobasilar acute ischemic stroke

Background: We report the case of sulfonylurea induced hypoglycemia manifesting as acute encephalopathy with focal neurological signs misdiagnosed as posterior circulation acute ischemic stroke (AIS) and discuss the potential effects of hypoglycemia on central nervous system, as well as its differentiation from AIS. Case presentation: A 64-year-old patient with type II diabetes treated with glimepiride was transferred to the Department of Neurology after the procedure of radical prostatectomy. On admission, the patient was unconscious with four limb paresis and bilateral Babinski sign. Non-contrast head CT and CT angiography vessels did not reveal any abnormalities. Due to exceeded therapeutic window the patient was disqualified from intravenous thrombolysis. At the admission hypoglycemia was observed and promptly corrected with the 5% dextrose infusion. For the next 72 hours repeated intravenous glucose infusions were needed to maintain its levels above 70 mg/dl. Based on the absence of ischemic changes on MRI and repeated decreases in glucose level for the next 3 days, glimepiride induced hypoglycemic encephalopathy was diagnosed. Within 24 hours of admission the patient regained consciousness and eventually presented four-limb paresis as a result of prolonged neuroglycopenia. Conclusions: Prolonged insufficient brain nutrition can result in permanent or long-lasting brain damage, manifesting as impaired consciousness and focal neurological signs. Perioperative sulfonylureas intake may result in prolonged hypoglycemia.