Plasma Ketone Concentrations Research Articles

#976 Empagliflozin limits AKI incidence and severity following cardiac surgery: an open-label phase IV randomized pilot study

Abstract Background and Aims Cardiac surgery-associated acute kidney injury (CSA-AKI) is a frequent complication of cardiac surgery assisted by cardiopulmonary bypass (CPB). Currently, no effective preventative strategies exist to reduce the incidence of acute kidney injury (AKI). Sodium-glucose transport protein 2 (SGLT2) inhibitors are effective in reducing the incidence of AKI in studies conducted in patients with chronic kidney disease. Therefore, we hypothesized that perioperative SGLT2 inhibition could reduce the incidence of CSA-AKI. Method In this open-label phase IV, randomized, parallel-group, balanced (1:1), pilot study, adult patients undergoing elective cardiac surgery with CPB were randomized to receive 10 mg empagliflozin per os once daily three days before surgery until two days after surgery, or standard care. The primary outcome was AKI incidence according to the Kidney Disease: Improving Global Outcomes (KDIGO) criteria. Other outcomes included hypoxia-inducible factor 1 alpha (HIF1A) and urinary Kidney Injury Molecule (KIM-1), urinary neutrophil gelatinase associated lipocalin (NGAL) and metabolic parameters such as plasma ketone and glucose concentrations. Results Between March 2022 and April 2023, 60 patients were randomized to empagliflozin (n = 29) or control (n = 31). All patients who underwent cardiac surgery with CPB were included in the intention-to-treat analysis (n = 25; empagliflozin group, n = 30; control group). SGLT2 inhibition significantly reduced the incidence of all stages of AKI (20% vs 66.7%; absolute difference 46%, 95% CI .13 to .63, P < .001). This decline in AKI incidence was reflected in the kidney biomarkers. SGLT2 inhibition also significantly reduced the number of patients with postoperative hyperglycemia (28% vs 60%; absolute difference 32%, 95% CI −56.8 to −7.2, P = .029). We observed no differences in the incidence of neither ketoacidosis nor hypoglycemic events. Conclusion Perioperative SGLT2 inhibition, compared with standard of care, demonstrated a significant reduction in AKI incidence rates. These findings merit validation in a larger placebo-controlled trial which is currently ongoing. Supplementary figures:

Distinct Mechanisms Responsible for the Increase in Glucose Production and Ketone Formation Caused by Empagliflozin in T2DM Patients.

To examine the mechanisms responsible for the increase in glucose and ketone production caused by empagliflozin in patients with type 2 diabetes mellitus (T2DM). Twelve subjects with T2DM participated in two studies performed in random order. In study 1, endogenous glucose production (EGP) was measured with 8-h infusion of 6,6,D2-glucose. Three hours after the start of 6,6,D2-glucose infusion, subjects ingested 25 mg empagliflozin (n = 8) or placebo (n = 4), and norepinephrine (NE) turnover was measured before and after empagliflozin ingestion with 3H-NE infusion. Study 2 was similar to study 1 but performed under pancreatic clamp conditions. When empagliflozin was ingested under fasting conditions, EGP increased by 31% in association with a decrease in plasma glucose (-34 mg/dL) and insulin (-52%) concentrations and increases in plasma glucagon (+19%), free fatty acid (FFA) (+29%), and β-hydroxybutyrate (+48%) concentrations. When empagliflozin was ingested under pancreatic clamp conditions, plasma insulin and glucagon concentrations remained unchanged, and the increase in plasma FFA and ketone concentrations was completely blocked, while the increase in EGP persisted. Total-body NE turnover rate was greater in subjects receiving empagliflozin (+67%) compared with placebo under both fasting and pancreatic clamp conditions. No difference in plasma NE concentration was observed in either study. The decrease in plasma insulin and increase in plasma glucagon concentration caused by empagliflozin is responsible for the increase in plasma FFA concentration and ketone production. The increase in EGP caused by empagliflozin is independent of the change in plasma insulin or glucagon concentrations and is likely explained by the increase in NE turnover.

β-Hydroxybutyrate Oxidation Is Reduced and Hepatic Balance of Ketone Bodies and Free Fatty Acids Is Unaltered in Carnitine-Depleted, Pivalate-Treated Rats

These experiments were designed to determine whether carnitine depletion in the rat due to pivalate administration causes reduced β-hydroxybutyrate oxidation and alterations in hepatic balance of ketone bodies and free fatty acids, relative to control rats. Male rats were given 20 mmol/L sodium pivalate for 2 wk to induce a secondary carnitine deficiency. Control animals were given 20 mmol/L sodium bicarbonate in their drinking water. In the ketone utilization experiment, rats were food-deprived for 24 h and infused with the sodium salt of β-hydroxybutyrate to maintain total plasma ketone concentrations between 6.0 and 10.0 mmol/L. After a bolus of 3-hydroxy[3-14C]butyrate, the recovery of expired 14CO2 collected during the ensuing 100 main was significantly lower in the pivalate-treated rats than in the controls (P < 0.05). In the second experiment, blood samples from pivalate-treated and control rats were collected from the abdominal aorta, portal vein and hepatic vein to determine the hepatic balance (hepatic input — hepatic output) of ketone bodies and free fatty acids. No significant differences were seen between the two treatment groups for either ketone bodies or free fatty acids. We conclude that the higher plasma ketone concentrations seen in food-deprived, pivalate-treated rats were due to a lower rate of ketone utilization. No evidence of pivalate influence upon ketone production was found.

ODP175 COVID-19 Induced Euglycemic Diabetic Ketoacidosis in a Patient taking Sodium-Glucose Cotransporter-2 Inhibitors

Abstract From the U.S., under to American Diabetes Association, diabetic ketoacidosis (DKA) is accountable for around 6.3 percent of all hospitalization and 0.4% of all mortality annually. Unregulated hyperglycemia (&amp;gt;250 mg/dL), significant anion gaps, metabolic acidosis, and an increased plasma ketone concentration are the manifestations of diabetic ketoacidosis. Despite this, DKA can occur in the vicinity of an average bloodstream sugar level (less than 200 mg/dL); this is described as euglycemic DKA (eu-DKA). The Sodium-glucose Cotransporter-2 (SGLT2) inhibitors are being used in the management of type 2 diabetes, given its favorable side effect of weight loss and improved cardiovascular mortality. Still, at the same, can cause in rare occasions eu-DKA. The hospitalization of a patient taking Empagliflozin at home presented to the emergency department complaining of shortness of breath, fever, chills, and productive cough for one week with eu-DKA and extreme acidemia in the setting of a confirmed COVID-19 infection that had remained persistent for eight days before presentations are described in this medical abstract. Eu-DKA is uncommon in the population, which increases the possibility of misdiagnosis in patients. In light of the COVID-19 epidemic, there is an immediate demand for increased public knowledge of the condition. Keywords: COVID-19, Diabetes, Glucose Metabolism, SARS-2, SGLT2 Inhibitor, Type 2 Diabetes Presentation: No date and time listed

54-LB: Distinct Mechanisms Are Responsible for the Increase in Endogenous Glucose Production and Ketone Formation following Empagliflozin in T2DM Patients

Aim: To examine the mechanisms responsible for the increase in glucose and ketone production caused by SGLT2 inhibition with empagliflozin in T2DM patients. Research Design and Methods: 12 T2DM subjects (Age = 53; BMI = 31.7; HbA1c = 7.4%) participated in two studies performed in random order. At 0700h following an overnight fast subjects received an 8-hour infusion of 6,6D2-glucose to measure endogenous (hepatic) glucose production. At 0900 h an infusion of 3H-norepinephrine was started. At 1000h subjects ingested 25 mg of empagliflozin (n=8) or matching placebo (n=4) and were followed for 5 hours (1500 h) . Within 1 week subjects returned for a repeat study with pancreatic clamp to maintain plasma insulin and glucagon concentrations constant at the basal level. As per study one, subjects ingested empagliflozin 25 mg or placebo prior to the pancreatic clamp. Results: When empagliflozin was ingested under fasting conditions, EGP increased by 31% in association with a decrease in plasma glucose (-34 mg/dl) and insulin (-52%) concentrations and increases in plasma glucagon (+19%) , FFA (+29%) and β-hydroxybutyrate (β-HB) (+48%) concentrations. When empagliflozin was ingested under pancreatic clamp conditions, plasma insulin and glucagon concentrations remained unchanged, and the increase in plasma FFA and ketone concentrations was completely blocked, while the increase in EGP persisted. Total-body NE turnover rate increased significantly in subjects receiving empagliflozin (+67%) compared to placebo under both fasting and pancreatic clamp conditions. No difference in plasma norepinephrine concentration was observed in either study. Conclusion: The decrease in plasma insulin and increase in plasma glucagon concentration caused by empagliflozin is responsible for the increase in plasma FFA concentration and ketone production. The increase in EGP caused by empagliflozin is independent of the change in plasma insulin or glucagon concentrations and is explained by the increase in total-body NE turnover. Disclosure S. Abdelgani: None. J. M. Adams: None. G. Daniele: n/a. F. Almulla: None. R. A. Defronzo: Advisory Panel; AstraZeneca, Boehringer Ingelheim International GmbH, Intarcia Therapeutics, Inc., Novo Nordisk, Research Support; AstraZeneca, Boehringer Ingelheim International GmbH, Merck &amp; Co., Inc., Speaker’s Bureau; AstraZeneca. M. Abdul-ghani: None. M. Abu-farha: None. S. Del prato: Advisory Panel; Applied Therapeutics, Eli Lilly and Company, Novartis Pharmaceuticals Corporation, Novo Nordisk A/S, Sanofi, Consultant; Menarini Group, Research Support; AstraZeneca, Boehringer Ingelheim International GmbH, Speaker’s Bureau; AstraZeneca, Boehringer Ingelheim International GmbH, Eli Lilly and Company, Merck &amp; Co., Inc., Sanofi, Stock/Shareholder; Novo Nordisk A/S. Funding National Institute of Health, Boehringer Ingelheim provided empagliflozin and placebo

Isonitrogenous low-carbohydrate diet elicits specific changes in metabolic gene expression in the skeletal muscle of exercise-trained mice.

With the renewed interest in low-carbohydrate diets (LCDs) in the sports field, a few animal studies have investigated their potential. However, most rodent studies have used an LCD containing low protein, which does not recapitulate a human LCD, and the muscle-specific adaptation in response to an LCD remains unclear. Therefore, we investigated the effects of two types of LCDs, both containing the same proportion of protein as a regular diet (isonitrogenous LCD; INLCD), on body composition, exercise performance, and metabolic fuel selection at the genetic level in the skeletal muscles of exercise-trained mice. Three groups of mice (n = 8 in each group), one fed a regular AIN-93G diet served as the control, and the others fed either of the two INLCDs containing 20% protein and 10% carbohydrate (INLCD-10%) or 20% protein and 1% carbohydrate (INLCD-1%) had a regular exercise load (5 times/week) for 12 weeks. Body weight and muscle mass did not decrease in either of the INLCD-fed groups, and the muscle glycogen levels and endurance capacity did not differ among the three groups. Only in the mice fed INLCD-1% did the plasma ketone concentration significantly increase, and gene expression related to glucose utilization significantly declined in the muscles. Both INLCD-1% and INLCD-10% consumption increased gene expression related to lipid utilization. These results suggest that, although INLCD treatment did not affect endurance capacity, it helped maintain muscle mass and glycogen content regardless of the glucose intake restrictions in trained mice. Moreover, an INLCD containing a low carbohydrate content might present an advantage by increasing lipid oxidation without ketosis and suppressing muscle glucose utilization.

Effect of elevated plasma ketones on cardiac efficiency

BackgroundThe mechanism(s) responsible for the cardiac benefits of SGLT2 inhibitors remain unknown. Specific AimTo examine the effect of increased plasma ketone concentration (with infusion of beta-hydroxybutyrate [BOHB]) on LV function and myocardial glucose uptake. MethodsTwo groups (6 per group) of T2DM with HFrEF (<45%) were studied. Group I (Age=59; BMI=31 kg/m2; A1c = 7.2%; EF=41%) received in random order a 6-hour BOHB infusion (Prime =1.5 mg/kg.min, then 0.75 mg/kg.min) or 6-hour HCO3 infusion with matching volume (control). Group II (Age=56; BMI=34 kg/m2; A1c=7.2%; EF=38%) received a 3-hour BOHB infusion at a higher rate (Prime=4.0 mg/kg.min, then 2.0 mg/kg.min). A cardiac MRI was performed before and after each infusion. Additionally, Group I underwent a PET study with 18F-2-DOG and 15O. ResultsGroups I and II achieved plasma ketone levels of 1.4 and 2.5 mmol/L, respectively. In Group II, BOHB infusion significantly (P<0.01) increased CO and EF, whereas in Group I the increase in CO and EF tend toward significance (p=0.06), suggesting a dose-dependent response to the increase in plasma ketone concentration. NaHCO3 infusion had no effect on any cardiac indices (Fig.1). Myocardial blood flow increased significantly (P<0.01) in both Group I and II. Myocardial glucose uptake was not altered by BOHB infusion. ConclusionIn patients with T2DM and HFrEF, a physiologic increase in plasma ketone concentration significantly increased LV function and myocardial blood flow without affecting cardiac glucose metabolism. These results suggest that altered myocardial substrate metabolism can be employed therapeutically to improve cardiac function in HFrEF.

SGLT2 Inhibition by Dapagliflozin Attenuates Diabetic Ketoacidosis in Mice with Type-1 Diabetes

SGLT2 inhibitors increase plasma ketone concentrations. It has been suggested that insulinopenia, along with an increase in the counter-regulatory hormones epinephrine, corticosterone, glucagon and growth hormone, can induce ketoacidosis, especially in type-1 diabetes (T1DM). Dehydration precipitates SGLT2 inhibitor-induced ketoacidosis in type-2 diabetes. We studied the effects of dapagliflozin and water deprivation on the development of ketoacidosis and the associated signaling pathways in T1DM mice. C57BL/6 mice were fed a high-fat diet. After 7days, some mice received intraperitoneal injection of streptozocin + alloxan (STZ/ALX). The treatment groups were control + water at lib; control + dapagloflozin + water at lib; control + dapagloflozin + water deprivation; STZ/ALX + water at lib; STZ/ALX + water deprivation; STZ/ALX + dapagloflozin + water at lib; STZ/ALX + dapagloflozin + water deprivation. Dapagliflozin was given for 7days. In the morning of day 18, food was removed, and water was removed in the water deprivation groups. ELISA, rt-PCR, and immunoblotting were used to assess blood, heart, liver, white and brown adipose tissues. The T1DM mice had ketoacidosis even without water deprivation. Water deprivation increased plasma levels of β-hydroxybutyrate, acetoacetate, corticosterone, and epinephrine and reduced the levels of adiponectin in T1DM mice. Interleukin (IL) 1β, IL-6, IL-8, and TNFα were also increased in the T1DM mice with water deprivation. Dapagliflozin attenuated the changes in the T1DM mice without and with water deprivation. Likewise, water deprivation increased the activation of the inflammasome in the heart, liver, and white fat of the T1DM mice and dapagliflozin attenuated these changes. Dapagliflozin reduced the mRNA levels of glucagon receptors in the liver and the increase in GPR109a in white and brown fat. In the liver, dapagliflozin increased AMPK phosphorylation, and attenuated the phosphorylation of TBK1 and the activation of NFκB. Dapagliflozin reduced ketone body levels and attenuated the activation of NFκB and the activation of the inflammasome in T1DM mice with ketoacidosis.

High-fat versus high-carbohydrate diets for optimal higher intensity endurance exercise performance: and the winner is….

High-fat versus high-carbohydrate diets for optimal higher intensity endurance exercise performance: and the winner is….

Inducing ketogenesis via an enteral formulation in patients with acute brain injury:a phase II study

ABSTRACTObjective: Although extensively studied in children, the safety and tolerability of ketone supplementation in adults is unclear, particularly in the acute brain injury population. The purpose of this study was to examine the feasibility and safety of inducing ketosis using an enteric ketogenic formulation and determine its impact on intracranial and cerebral perfusion pressures and metabolic parameters.Methods: Prospective interventional Phase II trial of ventilated critically ill patients with acute brain injury administered a ketogenic feed over a 6 day period.Results: 20 patients were recruited, 5 females and 15 males, 3 with stroke, 2 with subarachnoid haemorrhage and 15 with traumatic brain injury. Feeds were well tolerated with 19 patients completing study. There was a significant increase in both plasma beta-hydroxybutyrate and acetoacetate from 0.24± 0.31 mmol/l and 0.19 ± 0.16 mmol/l to 0.61 ± 0.53 mmol/l (p =0.0005) and 0.52 ± 0.40 mmol/l (p<0.0001) respectively over the 6 day period. Total daily Ketocal® caloric intake was positively correlated with plasma beta-hydroxybutyrate concentrations (p=0.0011). There was no significant correlation between the cerebral hypertension and cerebral hypoperfusion indices and plasma ketone concentrations. In 95% of patients there were no clinically significant changes in acid/base status over the 6 days with pH remaining within normal range.Conclusion: In patients with acute brain injury, an enterally administered ketogenic formulation increased plasma ketone concentrations, was well tolerated, did not impact on cerebral hemodynamics and can be safely administered.Clinical trial registered at the Australian New Zealand Clinical Trials Registry (ACTRN12616000332426)Abbreviations: BHB: betahydroxybutyrate; AcAc: acetoacetate; ABI: acute brain injury; TBI: traumatic brain injury; CSF: cerebrospinal fluid; SAH: subarachnoid injury; CVA: cerebrovascular accidents; ICP: intracranial pressure; CPP: cerebral perfusion pressure; ICU: intensive care unit; EVD: external ventricular device; CHI: cerebral hypoperfusion index; IHI: intracranial hypertension index; GCS: Glasgow Coma Scale

Acute Ketone Supplementation and Exercise Performance: A Systematic Review and Meta-Analysis of Randomized Controlled Trials.

To determine the acute effects of ketone supplementation on exercise performance (primary outcome) and physiological and perceptual responses to exercise (secondary outcomes). A systematic search was conducted in PubMed, Web of Science, and SPORTDiscus (since inception to July 21, 2019) to find randomized controlled trials assessing the effects of acute ketone supplementation compared with a drink containing no ketones (ie,control intervention). The standardized mean difference (Hedges g) between interventions and 95% confidence interval (CI) were computed using a random-effects model. Thirteen studies met all inclusion criteria. No significant differences were observed between interventions for overall exercise performance (Hedges g = -0.05; 95% CI, -0.30 to 0.20; P = .68). Subanalyses revealed no differences between interventions when analyzing endurance time-trial performance (g = -0.04; 95% CI, -0.35 to 0.28; P = .82) or when assessing the separate effects of supplements containing ketone esters (g = -0.07; 95% CI, -0.38 to 0.24; P = .66) or salts (g = -0.02; 95% CI, -0.45 to 0.41; P = .93). All studies reported increases in plasma ketone concentration after acute ketone supplementation, but no consistent effects were reported on the metabolic (plasma lactate and glucose levels), respiratory (respiratory exchange ratio, oxygen uptake, and ventilatory rate), cardiovascular (heart rate), or perceptual responses to exercise (rating of perceived exertion). The present findings suggest that ketone supplementation exerts no clear influence on exercise performance (from sprints to events lasting up to ∼50min) or metabolic, respiratory, cardiovascular, or perceptual responses to exercise. More research is needed to elucidate if this strategy could provide ergogenic effects on other exercise types (eg,ultraendurance exercise).

Pioglitazone prevents the increase in plasma ketone concentration associated with dapagliflozin in insulin-treated T2DM patients: Results from the Qatar Study.

Because of the unique mechanism of action of sodium-glucose co-transport inhibitors (SGLT2i), which is independent of insulin secretion and insulin action, members of this class of drugs effectively lower plasma glucose concentration when used in combination with all other antidiabetic agents, including insulin. Increased plasma ketone concentration has been reported in association with SGLT2i initiation, which, under certain clinical conditions, has developed into diabetic ketoacidosis. The daily insulin dose often is reduced at the time of initiating SGLT2i therapy in insulin-treated patients to avoid hypoglycaemia. However, reduction of insulin dose can increase the risk of ketoacidosis. In the present study, we examined the effect of the addition of dapagliflozin plus pioglitazone on plasma ketone concentration in insulin-treated T2DM patients and compared the results to the effect of dapagliflozin alone. A total of 18 poorly controlled, insulin-treated T2DM participants in the Qatar Study received dapagliflozin (10 mg) plus pioglitazone (30 mg), and 10 poorly controlled non-insulin-treated T2DM patients received dapagliflozin (10 mg) alone for 4 months. Dapagliflozin plus pioglitazone produced a robust decrease in HbA1c (-1.4%) and resulted in a 50% reduction in daily insulin dose, from 133 to 66 units, while dapagliflozin alone caused a 0.8% reduction in HbA1c. Dapagliflozin caused a four-fold increase in fasting plasma ketone concentration, while the combination of pioglitazone plus dapagliflozin was not associated with a significant increase (0.13 vs 0.15 mM) in plasma ketone concentration or in risk of hypoglycaemia. These results demonstrate that the addition of pioglitazone to dapagliflozin prevents the increase in plasma ketone concentration associated with SGLT2i therapy.

Determinants of the increase in ketone concentration during SGLT2 inhibition in NGT, IFG and T2DM patients.

To examine metabolic factors that influence ketone production after sodium-glucose cotransport inhibitor (SGLT2) administration. Fasting plasma glucose (FPG), insulin, glucagon, free fatty acid and ketone concentrations were measured in 15 type 2 diabetes mellitus (T2DM) and 16 non-diabetic subjects before and at day 1 and day 14 after treatment with empagliflozin. Empagliflozin caused a 38 mg/dL reduction in FPG concentration in T2DM patients. However, it caused only a small but significant (7 mg/dL) reduction in the FPG concentration in impaired fasting glucose (IFG) subjects and did not affect FPG concentration in normal glucose tolerant (NGT) subjects. Empagliflozin caused a significant increase in mean plasma glucagon, free fatty acid (FFA) and ketone concentrations in T2DM subjects. However, empagliflozin did not cause a significant change in mean plasma insulin, glucagon or ketone concentrations in non-diabetic subjects. An index that integrates change in plasma glucose, insulin and FFA concentration at day 1 strongly correlates with plasma ketone concentration at day 1 (r = 0.85, P < .001) and day 14 (r = 0.63, r = 0.01) and predicts, with 86% sensitivity and 83% specificity, subjects at the top tertile for plasma ketone concentration after empagliflozin treatment. Results of the present study demonstrate that SGLT2 inhibition exerts different metabolic effects in non-diabetic individuals as compared to diabetic patients.

Serial changes in plasma ketone concentrations in patients with acute brain injury

ObjectiveAcute brain injury (ABI) is a catastrophic event, leading to disruption of the normal cerebral metabolic pathways and a subsequent cerebral energy deficit. Ketones (beta-hydroxybutyrate (BHB) and acetoacetate) may represent an alternative metabolic substrate with the potential to improve cerebral energy supply and decrease injury. The purpose of this study was to evaluate baseline ketone concentrations in the ABI population.MethodsThirty-eight patients with ABI were enrolled into the study and followed for up to 7 days. We collected arterial blood samples immediately after admission and daily to measure the levels of BHB and acetoacetate. Where possible, matching cerebrospinal fluid (CSF) specimens were also collected.ResultsDuring the study period, plasma BHB levels were increased initially but normalized by day 3 while acetoacetate levels remained within the normal range. The change in BHB was significant. There were 30 observations in 10 patients where BHB could be measured in both blood and CSF. When the data were averaged over patients there was a weak correlation between blood and CSF BHB (Spearman’s ρ = 0.62, p = 0.054).ConclusionBlood ketone concentrations remain low within the ABI population. An external source of ketones will be required to increase blood concentrations to clinically relevant levels.

Effect of a ketogenic meal on cognitive function in elderly adults: potential for cognitive enhancement.

Glucose is the principal energy substrate for the brain, although ketone bodies are an effective alternative. Evidence suggests that elevation of plasma ketone body levels through oral intake of medium chain triglycerides (MCTs) may improve cognitive function. We tried to examine the possible effects of a ketogenic meal serving on cognition in elderly non-demented subjects. Subjects were 19 non-demented elderly adults over 60years old (13 females; mean age: 66.1±2.9years) who underwent neurocognitive tests 90 and 180min after oral intake of a ketogenic meal (Ketonformula®) containing 20g of MCTs and an isocaloric placebo meal without MCTs on separate days. Elevation of plasma ketone concentration after intake of a single ketogenic meal containing 20g of MCTs was confirmed (all p<0.001). As for cognition, improvements were observed in the digit span test, Trail-Making Test B, and the global score (Z=-2.4, p=0.017) following the ketogenic meal and the change in the executive functioning score was positively correlated with that of the plasma β-hydroxybutyrate level. The cognition-enhancing effect was observed predominantly for individuals who had a relatively low global score at baseline (Z=-2.8, p=0.005), compared to individuals with a high global score (Z=-0.7, p=0.51). Plasma levels of ketone bodies were successfully increased after intake of the ketogenic meal. The ketogenic meal was suggested to have positive effects on working memory, visual attention, and task switching in non-demented elderly.

Dapagliflozin Enhances Fat Oxidation and Ketone Production in Patients With Type 2 Diabetes.

Insulin resistance is associated with mitochondrial dysfunction and decreased ATP synthesis. Treatment of individuals with type 2 diabetes mellitus (T2DM) with sodium-glucose transporter 2 inhibitors (SGLT2i) improves insulin sensitivity. However, recent reports have demonstrated development of ketoacidosis in subjects with T2DM treated with SGLT2i. The current study examined the effect of improved insulin sensitivity with dapagliflozin on 1) mitochondrial ATP synthesis and 2) substrate oxidation rates and ketone production. The study randomized 18 individuals with T2DM to dapagliflozin (n = 9) or placebo (n = 9). Before and after 2 weeks, subjects received an insulin clamp with tritiated glucose, indirect calorimetry, and muscle biopsies. Dapagliflozin reduced fasting plasma glucose (167 ± 13 to 128 ± 6 mg/dL) and increased insulin-stimulated glucose disposal by 36% (P < 0.01). Glucose oxidation decreased (1.06 to 0.80 mg/kg ⋅ min, P < 0.05), whereas nonoxidative glucose disposal (glycogen synthesis) increased (2.74 to 4.74 mg/kg ⋅ min, P = 0.03). Dapagliflozin decreased basal glucose oxidation and increased lipid oxidation and plasma ketone concentration (0.05 to 0.19 mmol/L, P < 0.01) in association with an increase in fasting plasma glucagon (77 ± 8 to 94 ± 13, P < 0.01). Dapagliflozin reduced the ATP synthesis rate, which correlated with an increase in plasma ketone concentration. Dapagliflozin improved insulin sensitivity and caused a shift from glucose to lipid oxidation, which, together with an increase in glucagon-to-insulin ratio, provide the metabolic basis for increased ketone production.

Hepatic mTORC1 Opposes Impaired Insulin Action to Control Mitochondrial Metabolism in Obesity

Dysregulated mitochondrial metabolism during hepatic insulin resistance may contribute to pathophysiologies ranging from elevated glucose production to hepatocellular oxidative stress and inflammation. Given that obesity impairs insulin action but paradoxically activates mTORC1, we tested whether insulin action and mammalian target of rapamycin complex 1 (mTORC1) contribute to altered invivo hepatic mitochondrial metabolism. Loss of hepatic insulin action for 2weeks caused increased gluconeogenesis, mitochondrial anaplerosis, tricarboxylic acid (TCA) cycle oxidation, and ketogenesis. However, activation of mTORC1, induced by the loss of hepatic Tsc1, suppressed these fluxes. Only glycogen synthesis was impaired by both loss of insulin receptor and mTORC1 activation. Mice with a double knockout of the insulin receptor and Tsc1 had larger livers, hyperglycemia, severely impaired glycogen storage, and suppressed ketogenesis, as compared to those with loss of the liver insulin receptor alone. Thus, activation of hepatic mTORC1 opposes the catabolic effects of impaired insulin action under some nutritional states.

Ketogenic response to cotreatment with bezafibrate and medium chain triacylglycerols in healthy humans

ObjectivesThe aim of this study was to compare the ketogenic effect of the peroxisome proliferator-activated receptor-α stimulator, bezafibrate (BEZA), alone or in combination with medium-chain triacylglycerols (MCTs) in healthy adults. MethodsEighteen healthy adults completed the study: 10 were given a therapeutic dose of BEZA (400 mg/d) for 8 wk followed by a further 4 wk of BEZA (400 mg/d) plus MCT (60 g/d). Eight other participants were given MCT alone (60 g/d) for 4 wk. All participants underwent identical metabolic study days: (a) pretreatment (the control), and after (b) BEZA combined with MCT (BEZA+MCT) or (c) an equal dose of MCT only. On the metabolic study days, a standard breakfast and lunch were given and blood samples were taken hourly to measure plasma ketones, glucose, and fatty acids. ResultsThe combination of BEZA+MCT increased ketones twofold during the metabolic study day. The addition of BEZA increased early ketogenic efficiency of MCT by 2.5-fold but did not result in higher peak or mean concentration of ketones during the metabolic study day. No other differences were seen in plasma metabolites or insulin during metabolic study days. On the final metabolic study day, MCT or BEZA+MCT had different effects on the plasma acetoacetate-to-β-hydroxybutyrate ratio compared with control. ConclusionsBEZA mildly potentiated the ketogenic action of MCT but did not increase peak plasma ketone concentration or overall ketone production during the metabolic study day.

Reciprocal inhibition of in vitro substrate movement into avian skeletal muscle

Plasma glucose and ketone concentrations are much higher in birds than in humans and birds exhibit resistance to insulin-mediated glucose uptake into muscle. Therefore, birds may offer a model in which to examine the effects of high plasma glucose and free fatty acid (FFA) concentrations on substrate preference. The present study examined the uptake of radiolabeled oleic acid (OA; C18:1) and radiolabeled glucose by skeletal muscle isolated from the forewing of English sparrows (Passer domesticus). In dose–response studies, unlabeled glucose and OA (20mM each) inhibited the uptake of their respective radiolabeled counterparts. To examine the effects of glucose on OA uptake, muscles were incubated for 60min in a buffer containing 20mM glucose with the addition of radiolabeled OA. This level of glucose significantly decreased radiolabeled OA uptake by 36%. Using the same methodology, 20mM OA significantly decreased radiolabeled glucose transport by 49%. Comparing control values for glucose (0.952±0.04μM/mg muscle) and OA uptake (2.20±0.29μM/mg muscle), it is evident that OA is preferentially taken up by avian skeletal muscle. As FFAs provide a greater amount of energy per mole (146 ATP/OA) than carbohydrates (36 ATP/glucose), storing and utilizing fats may be more energy-efficient for birds. As studies in mammals have shown that FFAs may impair glucose uptake pathways, it is suspected that high FFA uptake by avian skeletal muscle may induce their notably lower glucose transport.

Mind the gap! An unusual metabolic acidosis

In May, 2010, a 50-year-old woman presented to us with hip pain and a temperature of 37·5°C. She had a history of epilepsy and was taking phenobarbital, carbamazepine, and phenytoin. Her total white cell count was 12·2×109 per L, haemoglobin 152 g/L, and C-reactive protein 87·9 mg/L. Cultures of blood and fl uid aspirated from her hip grew fl ucloxacillin-sensitive Staphylococcus aureus. Our patient was treated with intravenous fl ucloxacillin 8 g and paracetamol 4 g daily. After 12 days, she became obtunded, tachypnoeic, tachycardic, and hypotensive, and she was admitted to the intensive care unit. Arterial blood gas analysis showed a profoundly high anion-gap metabolic acidosis (pH 7·277, pCO2 1·31 kPa, pO2 11·65 kPa, base excess –19·8 mmol/L, bicarbonate 4·5 mmol/L, sodium 128 mmol/L, potassium 2·6 mmol/L, chloride 96 mmol/L, anion gap 30·1 mmol/L). Her glucose was 10·1 mmol/L and lactate 2·15 mmol/L; renal function was normal (urea 4·9 mmol/L, creatinine 99 μmol/L). Urine dipstick was positive for ketones, but starvation ketosis was excluded because the plasma ketone concentration was not high enough to account for the acidosis (3-hydroxybutyrate 0·50 mmol/L, free fatty acids 0·86 mmol/L). The antibiotic regimen was changed to meropenem on the basis of fresh wound and urine cultures. We suspected a diagnosis of pyroglutamic acidaemia because of the history of sepsis treated with fl ucloxacillin and paracetomol. The diagnosis was confi rmed by high urinary concentration of 5-oxyproline (16 500 μmol/mmol creatinine). Her condition failed to improve despite optimal management of her sepsis and repeated sodium bicarbonate administration, so paracetamol treatment was stopped and she was treated with N-acetyl cysteine. Within 3 h of this change in treatment, inotropic support was weaned, and the acidosis was completely corrected within 12 h (pH 7·484, pCO2 3·29 kPa, pO2 11·57 kPa, base excess –4·4mmol/L, bicarbonate 18·1 mmol/L, anion gap 14·2mmol/L). She was ventilated for 13 days, and was discharged home after one month, having made a full recovery. Pyroglutamic acidaemia is an unusual metabolic acidosis caused by the accumulation of 5-oxyproline, occurring as a result of hereditary defects. Although such a defect is unlikely in our patient, her condition can be explained by glutathione depletion and drug-related disruption of the γ-glutamyl cycle (fi gure). Under normal circumstances, glutathione inhibits γ-glutamylcysteine synthetase, and mild depletion leads to increased enzyme activity and restoration of glutathione stores. However, severe depletion saturates glutathione synthetase, leading to an accumulation of γ-glutamylcysteine, which is converted by γ-glutamyl cyclotransferase to 5-oxyproline. Our patient had several reasons to have glutathione depletion. She was malnourished, and glutathione synth esis is sensitive to dietary intake of cysteine. Also, sepsis depletes glutathione in animals, and potentially in people. Our patient had had 12 days’ therapy with paracetamol, a metabolite of which, N-acetylbenzo quinonimine, irre versibly binds glutathione and reduces stores. Her anti-epileptic medications are hepatic enzyme inducers, and compete with paracetamol for metabolism, further depleting glutathione. Sex diff erences in glutathione transferase activity, and lower glutathione stores in women than in men, also make women more susceptible to pyroglutamic acidaemia. Finally, treatment with fl ucloxacillin inhibits the breakdown of 5-oxyproline by 5-oxyprolinase. Pyro glutamic acidaemia should be considered in cases of high anion-gap metabolic acidosis, after the common causes have been excluded, and particularly when the risk factors of female sex, starvation, sepsis, and concurrent paracetamol and fl ucloxacillin therapy are present. It has also been associated with renal impairment and abnormal liver function. If pyroglutamic acidaemia is suspected, causative medications should be stopped immediately, and urinary organic acids measured. Replenishment of glutathione stores with N-acetylcysteine may be benefi cial.