Experimental Hypoglycemia Research Articles

Real-life hypoglycaemia partially blunts the inflammatory response to experimental hypoglycaemia in people with type 1 diabetes.

To determine whether recent repeated exposure to real-life hypoglycaemia affects the pro-inflammatory response during a hypoglycemia episode. This was a post hoc analysis of a hyperinsulinaemic normoglycaemic-hypoglycaemic clamp study, involving 40 participants with type 1 diabetes. Glucose levels 1 week before the clamp were monitored using a Freestyle Libre 1. Blood was drawn during normoglycaemia and hypoglycaemia, and 24 hours after resolution of hypoglycaemia for measurements of inflammatory responses and counterregulatory hormone levels. We determined the relationship between the frequency and duration of spontaneous hypoglycaemia, and time below range (TBR) and the inflammatory response to experimental hypoglycaemia. On average, participants experienced 0.79 (0.43, 1.14) hypoglycaemia episodes per day, with a duration of 78 (47, 110) minutes and TBR of 5.5% (2.8%, 8.5%). TBR and hypoglycaemia frequency were inversely associated with the increase in circulating granulocyte and lymphocyte counts during experimental hypoglycaemia (P < .05 for all). A protein network consisting of DNER, IF-R, uPA, Flt3L, FGF-5 and TWEAK was negatively associated with hypoglycaemia frequency (P < .05), but not with the adrenaline response. Neither other counterregulatory hormones, nor hypoglycaemia awareness status, was associated with any of the inflammatory parameters markers. Repeated exposure to spontaneous hypoglycaemia is associated with blunted effects of subsequent experimental hypoglycaemia on circulating immune cells and the number of inflammatory proteins.

Association between recent exposure to continuous glucose monitoring-recorded hypoglycaemia and counterregulatory and symptom responses to subsequent controlled hypoglycaemia in people with type 1 diabetes.

Experimental hypoglycaemia blunts the counterregulatory hormone and symptom responses to a subsequent episode of hypoglycaemia. In this study, we aimed to assess the associations between antecedent exposure and continuous glucose monitoring (CGM)-recorded hypoglycaemia during a 1-week period and the counterregulatory responses to subsequent experimental hypoglycaemia in people with type 1 diabetes. Forty-two people with type 1 diabetes (20 females, mean ± SD glycated haemoglobin 7.8% ± 1.0%, diabetes duration median (interquartile range) 22.0 (10.5-34.9) years, 29 CGM users, and 19 with impaired awareness of hypoglycaemia) wore an open intermittently scanned CGM for 1 week to detect hypoglycaemic exposure before a standardized hyperinsulinaemic-hypoglycaemic [2.8 ± 0.1 mmol/L (50.2 ± 2.3 mg/dl)] glucose clamp. Symptom responses and counterregulatory hormones were measured during the clamp. The study is part of the HypoRESOLVE project. CGM-recorded hypoglycaemia in the week before the clamp was negatively associated with adrenaline response [β -0.09, 95% CI (-0.16, -0.02) nmol/L, p = .014], after adjusting for CGM use, awareness of hypoglycaemia, glycated haemoglobin and total daily insulin dose. This was driven by level 2 hypoglycaemia [<3.0 mmol/L (54 mg/dl)] [β -0.21, 95% CI (-0.41, -0.01) nmol/L, p = .034]. CGM-recorded hypoglycaemia was negatively associated with total, autonomic, and neuroglycopenic symptom responses, but these associations were lost after adjusting for potential confounders. Recent exposure to CGM-detected hypoglycaemia was independently associated with an attenuated adrenaline response to experimental hypoglycaemia in people with type 1 diabetes.

Counterregulatory hormone and symptom responses to hypoglycaemia in people with type 1 diabetes, insulin-treated type 2 diabetes or without diabetes: the Hypo-RESOLVE hypoglycaemic clamp study

AimThe sympathetic nervous and hormonal counterregulatory responses to hypoglycaemia differ between people with type 1 and type 2 diabetes and may change along the course of diabetes, but have not been directly compared. We aimed to compare counterregulatory hormone and symptom responses to hypoglycaemia between people with type 1 diabetes, insulin-treated type 2 diabetes and controls without diabetes, using a standardised hyperinsulinaemic-hypoglycaemic clamp.MaterialsWe included 47 people with type 1 diabetes, 15 with insulin-treated type 2 diabetes, and 32 controls without diabetes. Controls were matched according to age and sex to the people with type 1 diabetes or with type 2 diabetes. All participants underwent a hyperinsulinaemic–euglycaemic-(5.2 ± 0.4 mmol/L)-hypoglycaemic-(2.8 ± 0.13 mmol/L)-clamp.ResultsThe glucagon response was lower in people with type 1 diabetes (9.4 ± 0.8 pmol/L, 8.0 [7.0–10.0]) compared to type 2 diabetes (23.7 ± 3.7 pmol/L, 18.0 [12.0–28.0], p < 0.001) and controls (30.6 ± 4.7, 25.5 [17.8–35.8] pmol/L, p < 0.001). The adrenaline response was lower in type 1 diabetes (1.7 ± 0.2, 1.6 [1.3–5.2] nmol/L) compared to type 2 diabetes (3.4 ± 0.7, 2.6 [1.3–5.2] nmol/L, p = 0.001) and controls (2.7 ± 0.4, 2.8 [1.4–3.9] nmol/L, p = 0.012). Growth hormone was lower in people with type 2 diabetes than in type 1 diabetes, at baseline (3.4 ± 1.6 vs 7.7 ± 1.3 mU/L, p = 0.042) and during hypoglycaemia (24.7 ± 7.1 vs 62.4 ± 5.8 mU/L, p = 0.001). People with 1 diabetes had lower overall symptom responses than people with type 2 diabetes (45.3 ± 2.7 vs 58.7 ± 6.4, p = 0.018), driven by a lower neuroglycopenic score (27.4 ± 1.8 vs 36.7 ± 4.2, p = 0.012).ConclusionAcute counterregulatory hormone and symptom responses to experimental hypoglycaemia are lower in people with type 1 diabetes than in those with long-standing insulin-treated type 2 diabetes and controls.

Effect of hypoglycemia on baroreflex sensitivity in individuals with type 2 diabetes: implications for autonomic control of cardiovascular function in diabetes.

Hypoglycemia is associated with increased mortality, though the mechanisms underlying this association are not established. Hypoglycemia impairs the counterregulatory hormonal and autonomic responses to subsequent hypoglycemia. It is unknown whether hypoglycemia elicits a generalized impairment in autonomic control of cardiovascular function in individuals with type 2 diabetes. We tested the hypothesis that in individuals with type 2 diabetes, hypoglycemia impairs a key measure of cardiovascular autonomic homeostasis, baroreflex sensitivity. Sixteen individuals with well-controlled type 2 diabetes and without known cardiovascular disease were exposed to two 90-min episodes of experimental hypoglycemia (2.8mmol/L, 50mg/dL) on the same day. All individuals experienced a hypoglycemic-hyperinsulinemic clamp in the morning (AM clamp) and again in the afternoon (PM clamp). Baroreflex sensitivity was assessed using the modified Oxford method before the initiation of each hypoglycemic-hyperinsulinemic clamp, during the last 30min of hypoglycemia, and the following morning. A mixed effects model adjusting for sex, age, BMI, and insulin level, demonstrated a significant effect of hypoglycemia on baroreflex sensitivity. The study is registered at ClinicalTrials.gov (NCT03422471). Baroreflex sensitivity during PM hypoglycemia was reduced compared to baseline, during AM hypoglycemia, and the next day. Insulin levels positively correlated with baroreflex sensitivity at baseline and during AM hypoglycemia. Exposure to hypoglycemia impairs a key measure of autonomic control of cardiovascular function and, thus, may increase the risk of cardiac arrhythmias and blood pressure lability in individuals with type 2 diabetes. This effect is attenuated in part by increased insulin levels.

Relationship Between Hypoglycemia Awareness Status on Clarke/Gold Methods and Counterregulatory Response to Hypoglycemia.

ContextImpaired awareness of hypoglycemia (IAH) is characterized by the diminished ability to perceive symptoms of hypoglycemia. Gold and Clark questionnaires are commonly used to identify patients with IAH. The relationship between IAH status on questionnaires and a person’s symptom and epinephrine responses to hypoglycemia are not well understood.ObjectiveWe aimed to examine the relationship between hypoglycemia awareness status on Clarke and Gold questionnaires with both hormonal and symptomatic responses to experimental hypoglycemia.MethodsIn this university medical center study, we examined data from 78 subjects with type 1 diabetes (T1D) who completed both questionnaires and underwent a hyperinsulinemic hypoglycemic clamp (target glucose 50 mg/dL).ResultsClarke and Gold scores were highly correlated with one another (r = 0.82) and each had a moderate negative relationship with epinephrine (Clarke: r = -0.51, Gold: r = -0.50) and total symptom response (Clarke: r = −0.59, Gold: r = −0.57). However, 32% of the subjects were classified inconsistently by Clark vs Gold. A clustering analysis was done to examine how disagreement between the 2 questionnaires on IAH classification relates to epinephrine and symptoms responses during hypoglycemia. Subjects who had partial loss of symptoms or of epinephrine response were more likely to be classified inconsistently.ConclusionOur results show that IAH classification may be discordant between Clark and Gold questionnaires and that hypoglycemia awareness status on Clarke and Gold questionnaires poorly predicts hormonal and symptomatic responses to hypoglycemia in subjects with T1D and moderate blunting of symptoms or epinephrine.

Heterogeneity in Epinephrine Response to Experimental Hypoglycemia in Type 1 Diabetes and Controls.

ContextThe epinephrine response (Epi) to a first episode of hypoglycemia (HG) has been proposed to be predictive of Epi in subsequent HG and to provide insight into the risk for developing HG-associated autonomic failure (HAAF) in healthy controls (HCs).ObjectiveTo determine if Epi and symptom response (SR) to the first episode of HG predicts who will develop HAAF after exposure to recurrent HG in volunteers with type 1 diabetes (T1D) and in HCs.DesignReview of data collected between 2013 and 2019.SettingAcademic clinical research unit.Patients or ParticipantsVolunteers with T1D and HCs.InterventionsSubjects participated in a preinduction protocol where they were exposed to three 2-hour episodes of clamped HG over 2 days. Data collected during clamp 1 were compared with data collected during clamp 3.Main outcome measureDifference in Epi and SR.ResultsUsing the standard definition of HAAF in which HG-induced Epi during clamp 3 is at least 20% lower than during clamp 1, 21/28 HCs and 13/19 volunteers with T1D developed HAAF. Epi during clamp 1 was significantly higher in those subjects who developed HAAF than in those who did not in both groups (P = 0.02). If HAAF is defined as achieving a 20% reduction in HG-induced SR measured during clamp 3 compared with clamp 1, 10/27 HCs and 10/19 volunteers with T1D developed SR-based HAAF.ConclusionThere was heterogeneity in the response to the preinduction protocol. Epi during clamp 1 was higher than in clamp 3 in HCs and in those with T1D who developed HAAF.

The Effect of Fasting on QT Interval

Introduction: QT interval reflects the total duration of ventricular depolarization and repolarization in the ECG. Experimental hypoglycaemia and spontaneous clinical episodes of hypoglycaemia lead to the lengthening of the heart rate corrected QT interval or QTc. This is associated with elevated risk of sudden death. Objective: To find out the effect of fasting blood glucose levels on QT interval and the Corrected QT interval (QTc). Materials and Methods: Fasting and post prandial blood glucose levels and ECG of healthy young adults were studied and QT interval, RR interval and QTc were determined. Results: The fasting QTc came out to be 0.408+-0.020 as compared to the post prandial value of 0.380+-0.019. The student’s t test showed a highly significant value (p

47-OR: Acute Fluctuations in Plasma Glucose Affect Echocardiographic-Derived Measures of Systolic Function in Patients with Type 1 Diabetes

Insulin treatment in patients with type 1 diabetes (T1D) causes rapid and large fluctuations in plasma glucose (PG) concentrations, and patients with T1D and poor glycemic control have an increased risk of cardiovascular disease including heart failure. We evaluated echocardiographic changes in cardiac function during experimental hypoglycemia and rebound hyperglycemia in patients with T1D. Patients with T1D (age 52.8±11.4 years, HbA1c 7.5±0.8% [57.6±8.9 mmol/mol], BMI 25.7±3.1 kg/m2) underwent two clamp days in random order. Both clamp days included three steady-state phases: 1) a 45-min hyperinsulinemic euglycemic phase (PG=6 mmol/L); 2) a 60-min hyperinsulinemic hypoglycemic phase (PG=2.5 mmol/L), and 3) a 60-min recovery phase in either hyperglycemia or euglycaemia (Clamp A: PG: 20 mmol/L; Clamp B: PG: 6 mmol/L). Cardiac function was evaluated with echocardiography at each phase by a blinded observer. Acute hypoglycemia increased left ventricular ejection fraction (LVEF) (absolute change, Clamp A: 6.5% [5.0;8.1], P=0.0001; Clamp B: 6.2% [4.6;7.9], P&amp;lt;0.0001) and global longitudinal strain (GLS) (absolute change, Clamp A: -3.1% (-4.5;-1.6), P&amp;lt;0.001; Clamp B: -3.5% (-4.6;-2.3), P&amp;lt;0.0001) from baseline. In Clamp A during hyperglycemia, LVEF and GLS were increased compared to baseline euglycemia (5.0% [3.2;6.8] (P&amp;lt;0.0001) and 2.1% [-3.7;-0.6] (P&amp;lt;0.01), respectively). An increase in LVEF was also observed in the recovery phase in Clamp B despite normalization of PG for 60 min (2.1% [0.5;3.8], P&amp;lt;0.05). In the recovery phase, LVEF was greater during hyperglycemia in Clamp A (2.9% [1.0;4.7], P&amp;lt;0.01) compared to euglycaemia in Clamp B. In conclusion, our findings suggest that acute fluctuations in PG affect echocardiographic-derived measures of systolic function in patients with T1D. Disclosure C. R. Andreasen: None. F. K. Knop: Advisory Panel; Self; MSD Corporation, Novo Nordisk A/S, Sanofi, Consultant; Self; AstraZeneca, Boehringer Ingelheim Pharmaceuticals, Inc., Eli Lilly and Company, Novo Nordisk A/S, Pharmacosmos, Zealand Pharma A/S, Research Support; Self; Novo Nordisk A/S, Zealand Pharma A/S, Speaker’s Bureau; Self; AstraZeneca, Bayer AG, Boehringer Ingelheim Pharmaceuticals, Inc., Eli Lilly and Company, MSD Corporation, Novo Nordisk A/S. T. Vilsbøll: Consultant; Self; Amgen Inc., AstraZeneca, Boehringer Ingelheim Pharmaceuticals, Inc., Bristol-Myers Squibb Company, Gilead Sciences, Inc., Lilly Diabetes, Merck Sharp &amp; Dohme Corp., Mundipharma International, Novo Nordisk, Sanofi, Sun Pharmaceutical Industries Ltd. A. Andersen: None. P. G. Hagelqvist: None. K. U. Abelin: None. J. V. Lauritsen: None. P. G. Jørgensen: Speaker’s Bureau; Self; AstraZeneca. S. Engberg: None. J. J. Holst: Consultant; Self; Novo Nordisk, Other Relationship; Self; Antag Therapeutics, Bainan Biotech, MSD Corporation, Novo Nordisk, Other Relationship; Spouse/Partner; Antag Therapeutics, Bainan Biotech, Synklino ApS. U. Pedersen-bjergaard: Advisory Panel; Self; Novo Nordisk A/S, Sanofi-Aventis, Consultant; Self; Abbott, Speaker’s Bureau; Self; Novo Nordisk A/S. Funding Novo Nordisk Foundation (NNF17SA0031406)

Hypoglycemia Impairs Baroreflex Sensitivity: Implications for Autonomic Control of Cardiovascular Function in Diabetes

Background: Iatrogenic hypoglycemia is an unintended, though common, occurrence in individuals with diabetes. There is a clear association between hypoglycemia exposure and an increase in mortality in individuals with type 2 diabetes (T2DM). It is well-established that recurrent hypoglycemic episodes impair the counterregulatory hormone responses; however, it is yet to be determined if in T2DM there are more global effects of hypoglycemia on autonomic control of cardiovascular function (baroreflex sensitivity, BRS), as has been shown in healthy individuals. This is a clinically relevant knowledge gap as decreases in BRS are pro-arrhythmogenic and associated with decreases in mortality in individuals with diabetes. Objective: We tested the hypothesis that in individuals with T2DM, hypoglycemia impairs baroreflex sensitivity (BRS), a robust measure of cardiovascular autonomic control. Methods: Individuals with well-controlled T2DM and without known cardiovascular disease were exposed to two 90-minute episodes of experimental hypoglycemia (50 mg/dl) in the same day. All individuals experienced a hypoglycemic-hyperinsulinemic clamp in the morning (AM clamp) and again in the afternoon (PM clamp). BRS was assessed using the modified Oxford method (sequential administration of nitroprusside and phenylephrine) before the initiation of each hypoglycemic-hyperinsulinemic clamp, during the last 30 minutes of hypoglycemia, and the following day. Results: The study included 16 individuals with a diagnosis of T2DM (6 men and 10 women) with the following characteristics (mean ± SD): age 45 ± 11 years, BMI 32 ± 6 kg/m2, hemoglobin A1c 6.4 ± 0.9%, and diabetes duration 8 ± 5 years. At baseline, individuals with T2DM had a BRS of 7.7 ± 3.6 ms/mmHg, which is reduced compared to a BRS of 21.3 ± 13.8 ms/mmHg in a historical healthy control group of 54 subjects (p<0.001). A mixed effects model adjusting for sex, age, BMI, and insulin level, demonstrated a significant effect of hypoglycemia on BRS (p=0.008). Pairwise comparisons revealed a significant decrease in BRS during the PM clamp as compared with BRS assessed at baseline (5.5 ± 5.0 vs 7.7 ± 3.6 ms/mmHg, p=0.045), during the AM clamp (5.5 ± 5.0 vs 10.5 ± 5.6 ms/mmHg, p=0.43), and the following day (5.5 ± 5.0 vs 8.6 ± 3.8 ms/mmHg, p=0.33). Of note, there was no significant difference between BRS at baseline and during the AM clamp (p=0.44). Additionally, insulin levels positively and strongly correlated with BRS at baseline (R2 0.52) and during the AM clamp (R2 0.67). Discussion: Insulin may have a stimulatory effect on BRS during a hyperinsulinemic hypoglycemic clamp that counters the inhibitory effect of hypoglycemia during the first episode of hypoglycemia. However, with exposure to a second hypoglycemic clamp, BRS decreases. Conclusion: Individuals with T2DM have low BRS at baseline, which is further reduced after 2 episodes of hypoglycemia.

Hyperinsulinaemic\u2013hypoglycaemic glucose clamps in human research: a systematic review of the literature

Aims/hypothesisThe hyperinsulinaemic–hypoglycaemic glucose clamp technique has been developed and applied to assess effects of and responses to hypoglycaemia under standardised conditions. However, the degree to which the methodology of clamp studies is standardised is unclear. This systematic review examines how hyperinsulinaemic–hypoglycaemic clamps have been performed and elucidates potential important differences.MethodsA literature search in PubMed and EMBASE was conducted. Articles in English published between 1980 and 2018, involving adults with or without diabetes, were included.ResultsA total of 383 articles were included. There was considerable variation in essential methodology of the hypoglycaemic clamp procedures, including the insulin dose used (49-fold difference between the lowest and the highest rate), the number of hypoglycaemic steps (range 1−6), the hypoglycaemic nadirs (range 2.0–4.3 mmol/l) and the duration (ranging from 5 to 660 min). Twenty-seven per cent of the articles reported whole blood glucose levels, most venous levels. In 70.8% of the studies, a dorsal hand vein was used for blood sampling, with some form of hand warming to arterialise venous blood in 78.8% of these. Key information was missing in 61.9% of the articles.Conclusions/interpretationAlthough the hyperinsulinaemic–hypoglycaemic clamp procedure is considered the gold standard to study experimental hypoglycaemia, a uniform standard with key elements on how to perform these experiments is lacking. Methodological differences should be considered when comparing results between hypoglycaemic clamp studies.PROSPERO registrationThis systematic review is registered in PROSPERO (CRD42019120083).Graphical abstract

Infusion of N-acetyl cysteine during hypoglycaemia in humans does not preserve the counterregulatory response to subsequent hypoglycaemia.

AimAdministration of N‐acetyl cysteine (NAC) during hypoglycaemia will preserve the counterregulatory response to subsequent hypoglycaemia in healthy humans.MethodsThis was a randomized double‐blind cross over study where humans were given either a 60‐minute infusion of NAC (150 mg/kg) followed by a 4‐hour infusion of NAC (50 mg/kg) or saline starting 30 minutes before the initiation of a 2‐hour hypoglycaemic (HG) clamp at 8 am. After rest at euglycaemia for ~2 hours, subjects were exposed to a 2nd HG clamp at 2 pm and discharged home in euglycaemia. They returned the following day for a 3rd HG clamp at 8 am.ResultsTwenty‐two subjects were enrolled. Eighteen subjects completed the entire protocol. The epinephrine response during clamp 3 (171 ± 247 pg/mL) following clamp 1 NAC infusion was lower than the response during the clamp 1 NAC infusion (538 ± 392 pg/mL) (clamp 3 to clamp 1 NAC: P = .0013). The symptom response during clamp 3 (7 ± 5) following clamp 1 NAC infusion was lower than the response during the clamp 1 NAC infusion (16 ± 10) (clamp 3 to clamp 1 NAC: P = .0003). Nine subjects experienced rash, pruritus or nausea during NAC infusion.ConclusionWe found no difference in the hormone and symptom response to experimental hypoglycaemia measured in subjects who were administered NAC as opposed to saline the day before. This observation suggests that further development of NAC as a therapy for impaired awareness of hypoglycaemia in patients with diabetes may be unwarranted.

Lactate infusion increases brain energy content during euglycemia but not hypoglycemia in healthy men.

A special characteristic of the brain is the usage of lactate as alternative fuel instead of glucose to preserve its energy homeostasis. This physiological function is valid for sufficient cerebral glucose supply, as well as presumably during hypoglycemia, given that exogenous lactate infusion suppresses hormonal counterregulation. However, it is not yet clarified whether this effect is mediated by the use of lactate as an alternative cerebral energy substrate or any other mechanism. We hypothesized that under conditions of limited access to glucose (ie, during experimental hypoglycemia) lactate infusion would prevent hypoglycemia-induced neuroenergetic deficits in a neuroprotective way. In a randomized, double-blind, crossover study, lactate vs placebo infusion was compared during hyperinsulinemic-hypoglycemic clamps in 16 healthy young men. We measured the cerebral high-energy phosphate content-ie, adenosine triphosphate (ATP), phosphocreatine (PCr) and inorganic phosphate (Pi) levels-by 31 P-magnetic resonance spectroscopy as well as the neuroendocrine stress response. During euglycemia, lactate infusion increased ATP/Pi as well as PCr/Pi ratios compared with baseline values and placebo infusion. During hypoglycemia, there were no differences between the lactate and the placebo condition in both ratios. Hormonal counterregulation was significantly diminished upon lactate infusion. Our data demonstrate an elevated cerebral high-energy phosphate content upon lactate infusion during euglycemia, whereas there was no such effect during experimental hypoglycemia. Nevertheless, lactate infusion suppressed hypoglycemic hormonal counterregulation. Lactate thus adds to cerebral energy provision during euglycemia and may contribute to an increase in ATP reserves, which in turn protects the brain against neuroglucopenia under recurrent hypopglycemic conditions, eg, in diabetic patients.

Effect of once-weekly semaglutide on the counterregulatory response to hypoglycaemia in people with type 2 diabetes: A randomized, placebo-controlled, double-blind, crossover trial.

AimsTo investigate the effects of semaglutide vs placebo on glucagon and other counterregulatory hormones during hypoglycaemia in type 2 diabetes (T2D).MethodsIn this double‐blind, placebo‐controlled, single‐centre trial, we randomized 38 men and women (treated only with metformin) 1:1 to 2 12‐week crossover periods of once‐weekly subcutaneous semaglutide or placebo, each followed by a hypoglycaemic clamp procedure. The primary endpoint was change in glucagon concentration from target plasma glucose (PG) level 5.5 mmol/L to nadir (target 2.5 mmol/L).ResultsThe mean (range) participant age was 54.2 (41‐64) years, body mass index 29.4 (23.3‐36.1) kg/m2, glycated haemoglobin 60.8 (44.3‐83.6) mmol/mol (7.7 [6.2‐9.8]%), and diabetes duration 4.5 (0.3‐13.2) years. A total of 35 participants completed the trial and were included in the analyses. During the hypoglycaemic clamp from 5.5 mmol/L PG to nadir, the absolute change in mean glucagon concentration was similar for semaglutide vs placebo: 88.3 vs 83.1 pg/mL (estimated difference 5.2 pg/mL [95% confidence interval −7.7 to 18.1]). Concentrations of other counterregulatory hormones increased with both treatments, with a statistically significantly lower increase for noradrenaline and cortisol with semaglutide vs placebo. The glucose infusion rate to maintain constant clamp levels was similar for each treatment group, suggesting an overall similar counterregulatory response. The mean hypoglycaemic symptom score and proportion of participants recognizing hypoglycaemia during the study were lower for semaglutide vs placebo treatment at nadir, but cognitive function test results were similar. No new safety issues were observed for semaglutide.ConclusionsSemaglutide treatment did not compromise the counterregulatory glucagon response during experimental hypoglycaemia in people with T2D.

Intensive Hypoglycemia Avoidance and Improved Awareness of Hypoglycemia Associated with Partial Recovery Activation Lost in Hypoglycemia Unaware Patients with Type 1 Diabetes

Aim: The brain senses hypoglycemia and governs symptomatic, hormonal and behavioral responses to it. This study aimed to understand the differences in regional brain responses to experimental hypoglycemia between adults with type 1 diabetes (T1D) with intact hypoglycemia awareness [HA] and impaired awareness of hypoglycemia [IAH] and evaluate the impact of intensive hypoglycemia avoidance on these responses. Methods: We performed ASL fMRI scans to measure global and regional cerebral blood flow [CBF and rCBF] and measured symptomatic and hormonal responses to experimental hypoglycemia [47 mg/dl] in 15 HA T1D subjects and 22 subjects with IAH matched for age, HbA1c and duration of diabetes. Those with IAH underwent a hypoglycemia avoidance program including education, frequent contact and additional technology where required, including sensor augmented pump therapy with predictive low glucose suspend before being restudied with ASL FMRI at hypoglycemia. Results: Baseline scans: Global CBF increased in response to hypoglycemia in HA and IAH [HA 6.3% p=0.01; IAH 8.0%, p=0.03; HA vs. IAH p=NS]. There was greater increase in rCBF in thalamus, prefrontal cortex and orbitofrontal cortex in HA vs. IAH and greater reduction in rCBF in the hippocampus. Repeat scans: The hypoglycemia avoidance program improved subjective awareness [Gold score 6 ±1 vs. 4.2±1.9; p = 0.001] in the 12 completers. Compared to baseline scans, there was a trend to greater increase in rCBF in the anterior cingulate cortex in response to hypoglycemia [p=0.058], but no changes in the thalamus, prefrontal or orbitofrontal cortices. Conclusion: Intensive education and support can improve hypoglycemia awareness with some restoration of activation in the anterior cingulate cortex, but frontal changes are not restored suggesting cognitive responses to hypoglycemia may not be changed by these interventions. Disclosure P. Choudhary: Speaker's Bureau; Self; Medtronic MiniMed, Inc., Novo Nordisk Inc.. Advisory Panel; Self; Becton, Dickinson and Company, Sanofi-Aventis, Roche Diabetes Care Health and Digital Solutions, Lilly. M. Nwokolo: None. O. O'Daly: None. S.A. Amiel: Advisory Panel; Self; Medtronic MiniMed, Inc., Novo Nordisk A/S, Roche Diabetes Care Health and Digital Solutions. F.O. Zelaya: None.

The Morphological Changes of Uterus in Postnatal Development of Heifers

The Morphological Changes of Uterus in Postnatal Development of Heifers

Effects of Hypoglycemia on Circulating Stem and Progenitor Cells in Diabetic Patients.

Iatrogenic hypoglycemia is the most common acute diabetic complication, and it significantly increases morbidity. In people with diabetes, reduction in the levels of circulating stem and progenitor cells predicts adverse outcomes. To evaluate whether hypoglycemia in diabetes affects circulating stem cells and endothelial progenitor cells (EPCs). We performed an experimental hypoglycemia study (Study 1) and a case-control study (Study 2). Tertiary referral inpatient clinic. Type 1 diabetic patients (Study 1, n = 19); diabetic patients hospitalized for severe iatrogenic hypoglycemia, matched inpatient and outpatient controls (Study 2, n = 22/group). Type 1 diabetic patients underwent two in-hospital sessions of glucose monitoring during a breakfast meal with or without induction of hypoglycemia in random order. In Study 2, patients hospitalized for hypoglycemia and matched controls were compared. Circulating stem cells and EPCs were measured by flow cytometry based on the expression of CD34 and kinase insert domain receptor (KDR). In Study 1, the physiologic decline of CD34+KDR+ EPCs from 8 am to 2 pm was abolished by insulin-induced hypoglycemia in type 1 diabetic patients. In Study 2, diabetic patients hospitalized for severe iatrogenic hypoglycemia had significantly lower levels of CD34+ stem cells and CD34+KDR+ EPCs compared with diabetic inpatients or outpatient controls. In diabetic patients, a single mild hypoglycemic episode can compromise the physiologic EPC fluctuation, whereas severe hypoglycemia is associated with a marked reduction in stem cells and EPCs. These data provide a possible link between hypoglycemia and adverse outcomes of diabetes.

Cardiac Autonomic Regulation and Repolarization During Acute Experimental Hypoglycemia in Type 2 Diabetes.

Hypoglycemia is associated with increased cardiovascular mortality in trials of intensive therapy in type 2 diabetes mellitus (T2DM). We previously observed an increase in arrhythmias during spontaneous prolonged hypoglycemia in patients with T2DM. We examined changes in cardiac autonomic function and repolarization during sustained experimental hypoglycemia. Twelve adults with T2DM and 11 age- and BMI-matched control participants without diabetes underwent paired hyperinsulinemic clamps separated by 4 weeks. Glucose was maintained at euglycemia (6.0 mmol/L) or hypoglycemia (2.5 mmol/L) for 1 h. Heart rate, blood pressure, and heart rate variability were assessed every 30 min and corrected QT intervals and T-wave morphology every 60 min. Heart rate initially increased in participants with T2DM but then fell toward baseline despite maintained hypoglycemia at 1 h accompanied by reactivation of vagal tone. In control participants, vagal tone remained depressed during sustained hypoglycemia. Participants with T2DM exhibited greater heterogeneity of repolarization during hypoglycemia as demonstrated by T-wave symmetry and principal component analysis ratio compared with control participants. Epinephrine levels during hypoglycemia were similar between groups. Cardiac autonomic regulation during hypoglycemia appears to be time dependent. Individuals with T2DM demonstrate greater repolarization abnormalities for a given hypoglycemic stimulus despite comparable sympathoadrenal responses. These mechanisms could contribute to arrhythmias during clinical hypoglycemic episodes.

Impact of the TCF7L2 genotype on risk of hypoglycaemia and glucagon secretion during hypoglycaemia.

IntroductionIn healthy carriers of the T allele of the transcription factor 7-like 2 (TCF7L2), fasting plasma glucagon concentrations are lower compared with those with the C allele. We hypothesised that presence of the T allele is associated with a diminished glucagon response during hypoglycaemia and a higher frequency of severe hypoglycaemia (SH) in type 1 diabetes (T1DM).Material and methodsThis is a post hoc study of an earlier prospective observational study of SH and four mechanistic studies of physiological responses to hypoglycaemia. 269 patients with T1DM were followed in a one-year observational study. A log-linear negative binomial model was applied with events of SH as dependent variable and TCF7L2 alleles as explanatory variable. In four experimental studies including 65 people, TCF7L2 genotyping was done and plasma glucagon concentration during experimental hypoglycaemia was determined.ResultsIncidences of SH were TT 0.54, TC 0.98 and CC 1.01 episodes per patient-year with no significant difference between groups. During experimental hypoglycaemia, the TCF7L2 polymorphism did not influence glucagon secretion.DiscussionPatients with T1DM carrying the T allele of the TCF7L2 polymorphism do not exhibit diminished glucagon response during hypoglycaemia and are not at increased risk of severe hypoglycaemia compared with carriers of the C allele.

Can Ketones Help Rescue Brain Fuel Supply in Later Life? Implications for Cognitive Health during Aging and the Treatment of Alzheimer's Disease.

We propose that brain energy deficit is an important pre-symptomatic feature of Alzheimer’s disease (AD) that requires closer attention in the development of AD therapeutics. Our rationale is fourfold: (i) Glucose uptake is lower in the frontal cortex of people >65 years-old despite cognitive scores that are normal for age. (ii) The regional deficit in brain glucose uptake is present in adults <40 years-old who have genetic or lifestyle risk factors for AD but in whom cognitive decline has not yet started. Examples include young adult carriers of presenilin-1 or apolipoprotein E4, and young adults with mild insulin resistance or with a maternal family history of AD. (iii) Regional brain glucose uptake is impaired in AD and mild cognitive impairment (MCI), but brain uptake of ketones (beta-hydroxybutyrate and acetoacetate), remains the same in AD and MCI as in cognitively healthy age-matched controls. These observations point to a brain fuel deficit which appears to be specific to glucose, precedes cognitive decline associated with AD, and becomes more severe as MCI progresses toward AD. Since glucose is the brain’s main fuel, we suggest that gradual brain glucose exhaustion is contributing significantly to the onset or progression of AD. (iv) Interventions that raise ketone availability to the brain improve cognitive outcomes in both MCI and AD as well as in acute experimental hypoglycemia. Ketones are the brain’s main alternative fuel to glucose and brain ketone uptake is still normal in MCI and in early AD, which would help explain why ketogenic interventions improve some cognitive outcomes in MCI and AD. We suggest that the brain energy deficit needs to be overcome in order to successfully develop more effective therapeutics for AD. At present, oral ketogenic supplements are the most promising means of achieving this goal.

Disrupted Leptin Signaling in the Lateral Hypothalamus and Ventral Premammillary Nucleus Alters Insulin and Glucagon Secretion and Protects Against Diet-Induced Obesity.

Leptin signaling in the central nervous system, and particularly the arcuate hypothalamic nucleus, is important for regulating energy and glucose homeostasis. However, the roles of extra-arcuate leptin responsive neurons are less defined. In the current study, we generated mice with widespread inactivation of the long leptin receptor isoform in the central nervous system via Synapsin promoter-driven Cre (Lepr(flox/flox) Syn-cre mice). Within the hypothalamus, leptin signaling was disrupted in the lateral hypothalamic area (LHA) and ventral premammillary nucleus (PMV) but remained intact in the arcuate hypothalamic nucleus and ventromedial hypothalamic nucleus, dorsomedial hypothalamic nucleus, and nucleus of the tractus solitarius. To investigate the role of LHA/PMV neuronal leptin signaling, we examined glucose and energy homeostasis in Lepr(flox/flox) Syn-cre mice and Lepr(flox/flox) littermates under basal and diet-induced obese conditions and tested the role of LHA/PMV neurons in leptin-mediated glucose lowering in streptozotocin-induced diabetes. Lepr(flox/flox) Syn-cre mice did not have altered body weight or blood glucose levels but were hyperinsulinemic and had enhanced glucagon secretion in response to experimental hypoglycemia. Surprisingly, when placed on a high-fat diet, Lepr(flox/flox) Syn-cre mice were protected from weight gain, glucose intolerance, and diet-induced hyperinsulinemia. Peripheral leptin administration lowered blood glucose in streptozotocin-induced diabetic Lepr(flox/flox) Syn-cre mice as effectively as in Lepr(flox/flox) littermate controls. Collectively these findings suggest that leptin signaling in LHA/PMV neurons is not critical for regulating glucose levels but has an indispensable role in the regulation of insulin and glucagon levels and, may promote the development of diet-induced hyperinsulinemia and weight gain.