Suppression Of Endogenous Glucose Production Research Articles

1136-P: Glucose Kinetics during Oral Glucose Challenge following Administration of Exenatide and Dapagliflozin Alone and in Combination in Type 2 Diabetes

Aim: To examine the effect of SGLT2i on endogenous glucose production (EGP), tissue glucose disappearance (Rd), and urinary glucose excretion (UGE) following glucose ingestion. Study Design: 28 type 2 diabetes [T2D] patients (Age= 51±2 y; BMI=31.2±0.7; A1C=7.9±0.2%) received 8-hour 3-3H-glucose infusion after an overnight fast. Previously shown, EGP suppression by dapagliflozin (DAPA) compared to placebo (PCB) (Δ=-0.02±0.02 vs. -0.45±0.03, p<0.01 mg/kg.min) was impaired. On a separate day, subjects were randomized to receive 5-hour double-isotope (IV 3-[3H]-glucose and oral [14C]-glucose) OGTT (75-g) preceded by PCB, DAPA 10 mg, EXEN 5 µg, or DAPA+EXEN. Oral [RaO], EGP, Total and Tissue Rd, and UGE were calculated. Results: During 0-300-min, RaO was 65 g in DAPA, 59 g in PCB, 46 g in EXEN, and 48 g in DAPA+EXEN. UGE was 31±4 g in DAPA and 30±4 g in DAPA+EXEN, but only 3±1 g in EXEN and 10±3 g in PCB (p<0.001 vs. DAPA and DAPA+EXEN). Conclusion: The post-OGTT rise in PG was significantly reduced after DAPA+EXEN vs. each drug alone. This resulted from lower oral glucose appearance with greater UGE. During the OGTT, EGP suppression with DAPA (Δ = -0.8±0.1 mg/kg.min) was less than with PCB, EXEN, and DAPA/EXEN (p<0.05-0.01), while EGP suppression with DAPA/EXEN was similar to PCB but required a higher rise in insulin (p<0.05). Tissue glucose clearance was unchanged by any therapy. Disclosure M. Alatrach: None. C. Agyin: None. N. Laichuthai: None. O. Lavrynenko: None. J.M. Adams: None. M. Abdul-Ghani: None. C.L. Triplitt: Speaker’s Bureau; Self; AstraZeneca, Janssen Pharmaceuticals, Inc., Lilly Diabetes, Xeris Pharmaceuticals, Inc. R.A. DeFronzo: None. E. Cersosimo: None.

29-OR: Comparison of Empagliflozin and Sitagliptin on Ectopic Fat Accumulation and Tissue-Specific Insulin Sensitivity

Background: Ectopic fat accumulation is the major pathogenesis of insulin resistance, type 2 diabetes mellitus (T2DM), and cardiovascular diseases. To date, no prospective study compared the effects of sodium glucose cotransporter 2 inhibitors (SGLT2i) and dipeptidyl peptidase-4 inhibitors on ectopic fat accumulation and tissue-specific insulin sensitivity. Methods: This is the prospective, randomized, open-label, and blind-endpoint study in 44 Japanese patients with T2DM. Patients (HbA1c: 7.2±0.9%, known duration: 3.9±4.0 years, BMI: 29.1±4.8 kg/m2) were randomized to empagliflozin (Empa) add-on group or sitagliptin (Sita) add-on group, and treated for 12 weeks. The primary endpoint was the change of pericardial fat content estimated by magnetic resonance imaging. The secondary endpoints were the changes in the amount of intrahepatic, intra- and extra-myocellular lipid content estimated by proton magnetic resonance spectroscopy, and tissue-specific insulin sensitivity assessed by hyperinsulinemic-euglycemic clamp tests using stable isotope. Results: There was no difference in pericardial fat content between the groups. Interestingly, intrahepatic lipid content (IHL) was reduced significantly from baseline in Empa group compared to Sita (-23.0±26.3 vs. -3.9±19.8%, respectively, p<0.05). However, the change in clamped % suppression of endogenous glucose production was comparable between the groups. On the other hand, rate of glucose disappearance was significantly increased in Empa group compared to Sita (+18.5±55.2 vs. -8.6±20.2%, p<0.05), while the amount of intra- and extra-myocellular lipid content remained similar between the groups. Conclusion: This is the first study that compared Empa and Sita on ectopic fat content and tissue-specific insulin sensitivity. Empa significantly reduced IHL and increased insulin sensitivity in muscle compared to Sita. SGLT2i might be preferable in treatment of T2DM with hepatic steatosis. Disclosure S. Hiruma: None. F. Shigiyama: None. S. Hisatake: None. S. Mizumura: None. N. Shiraga: None. M. Hori: None. T. Ikeda: None. T. Hirose: Research Support; Self; Boehringer Ingelheim Pharmaceuticals, Inc., Daiichi Sankyo, Mitsubishi Tanabe Pharma Corporation, Ono Pharmaceutical Co., Ltd., Takeda Pharmaceutical Company Limited. Speaker’s Bureau; Self; AstraZeneca, Lilly Diabetes, Novo Nordisk Inc., Sanofi, Sumitomo Dainippon Pharma Co., Ltd. N. Kumashiro: Research Support; Self; Boehringer Ingelheim Pharmaceuticals, Inc. Speaker’s Bureau; Self; Novo Nordisk Inc., Ono Pharmaceutical Co., Ltd., Takeda Pharmaceutical Company Limited. Funding Nippon Boehringer Ingelheim Co., Ltd. (1245-0162)

4261 Insulin Sensitizing Effects of Vitamin D Mediated through Reduced Adipose Tissue Inflammation and Fibrosis: Evidence from a Human Randomized Trial and Mice Studies

OBJECTIVES/GOALS: Vitamin D [25(OH)D], known to have anti-inflammatory and anti-fibrotic effects in other tissues, may also impact adipose tissue. We designed parallel studies in humans and rodents to define the effects of vitamin D on adipose tissue inflammation and fibrosis, and on systemic insulin resistance. METHODS/STUDY POPULATION: We performed a randomized, double-blinded placebo-controlled trial to examine the effects of repleting vitamin D at to two levels (to >30 ng/ml and to > 50 ng/ml) in 25(OH)D-deficient (<20 ng/ml), insulin resistant, overweight-to-obese humans (n = 19). A comprehensive study of whole-body insulin action was undertaken with euglycemic stepped hyperinsulinemic clamp studies, both before (1st visit) and after administration of vitamin D or placebo (2nd visit and 3rd visit). Adipose tissue fibrosis and inflammation were quantified by ‘real-time’ rt-PCR and immunofluorescence. To determine whether vitamin D’s effects are mediated through adipocytes, we performed hyperinsulinemic clamp studies and adipose tissue analysis in an adipocyte-specific vitamin D receptor knockout (VDR KO) mouse model. RESULTS/ANTICIPATED RESULTS: 25(OH)D repletion (to >30 ng/ml) was associated with reductions in adipose tissue expression of inflammatory (0.6-0.7-fold decreased expression of TNF-α, IL-6, iNOS and PAI-1) and pro-fibrotic (0.4-0.8-fold decreased expression of TGF-β1, HiF1α, Collagen I, V, VI and MMP7) factors, decreased collagen VI immunofluorescence (p = 0.02) and improved hepatic insulin sensitivity in humans, with suppression of endogenous glucose production (EGP) (1.28 ± 0.20 vs 0.88 ± 0.18 mg/kg/min, p = 0.03). Compared to wild type (WT), VDR KO mice exhibited increased adipose tissue expression of several pro-inflammatory (Tnf-α, iNos, Pai-1, Mcp-1 and F4/80; 4-10 fold) and pro-fibrotic genes (Tgf-β1, Collagen VI, and Tsp1; 2-4 fold), in concert with hepatic insulin resistance (EGP 10 ± 3 vs 3 ± 2 mg/kg/min in WT, p = 0.021). DISCUSSION/SIGNIFICANCE OF IMPACT: Collectively, these complementary human and rodent studies establish a beneficial role of vitamin D to improve hepatic insulin resistance, likely by restraining adipose tissue inflammation and fibrosis. Thus, normalizing 25(OH)D levels could have metabolic benefits in targeted individuals. CONFLICT OF INTEREST DESCRIPTION: N/A

205-OR: Hepatic Protein Kinase C-e Is Necessary and Sufficient in Mediating Lipid-Induced Hepatic Insulin Resistance

Nonalcoholic fatty liver disease (NAFLD) is strongly associated with hepatic insulin resistance (HIR), however the key lipid species and molecular mechanisms linking these conditions are widely debated. In order to address these questions, we examined the metabolic impact of a liver-specific antisense oligonucleotide against PKCε and found that liver-specific PKCε knockdown ameliorated high-fat diet-induced HIR in rats, reflected by ∼2x increase in insulin-stimulated hepatic glycogen synthesis rate and improved insulin-mediated suppression of endogenous glucose production during a hyperinsulinemic-hyperglycemic (HH) clamp. This was associated with increased IRK Y1162 and Akt S473 phosphorylation and could be attributed to decreased PKCε-mediated IRK T1160 phosphorylation. Overexpressing a constitutively active PKCε (A159E) in the liver induced HIR in regular chow-fed rats, reflected by reduced insulin-stimulated glycogen synthesis rate during an HH clamp. This was associated with impaired IRK Y1162 and Akt S473 phosphorylation and could be attributed to increased PKCε-mediated IRK T1160 phosphorylation. We also developed a subcellular fractionation method to quantify diacylglycerol (DAG) stereoisomers and ceramides in the endoplasmic reticulum, mitochondria, plasma membrane (PM), lipid droplet and cytosol and applied this method to a cohort of obese human subjects with and without NAFLD and HIR. Liver PM sn-1,2 DAG content was ∼5x higher in HIR individuals with NAFLD compared to insulin-sensitive individuals without NAFLD, associated with ∼3x higher IRK T1160 phosphorylation, supporting the importance of PM sn-1,2 DAG-PKCε-IRK pT1160 pathway to mediate HIR in humans with NAFLD. In contrast there were no significant differences in ceramide content in any of the subcellular compartments. Conclusion: These data identify PM sn-1,2 DAGs as the key lipids that activate PKCε, and that hepatic PKCε is both necessary and sufficient in mediating HIR. Disclosure K. Lyu: None. D. Zhang: None. M. Kahn: None. M.R.S. Rodrigues: None. S. Hirabara: None. P. Luukkonen: None. S. Lee: None. S. Bhanot: None. J. Rinehart: None. N. Blume: Employee; Self; Novo Nordisk A/S. Stock/Shareholder; Self; Novo Nordisk A/S. M. Rasch: Employee; Self; Novo Nordisk A/S. Stock/Shareholder; Self; Novo Nordisk A/S. M.J. Serlie: None. J. Bogan: None. G. Cline: None. V. Samuel: None. G.I. Shulman: Advisory Panel; Self; AstraZeneca, Janssen Research & Development, LLC, Merck & Co., Inc. Advisory Panel; Spouse/Partner; Merck & Co., Inc. Consultant; Self; Novo Nordisk A/S. Consultant; Spouse/Partner; Novo Nordisk A/S. Other Relationship; Self; Gilead Sciences, Inc., iMetabolic Biopharma Corporation. Other Relationship; Spouse/Partner; iMetabolic Biopharma Corporation. Other Relationship; Self; Maze Therapeutics. Funding U.S. Public Health Service (R01DK116774, R01DK119968, R01DK113984, P30DK045735, R01 DK092661); U.S. Department of Veternas Affairs (I01BX000901)

1832-P: Palmitic Acid Esters of Hydroxy Stearic Acids Reduce Endogenous Glucose Production through GPR43 Activation

Palmitic Acid esters of Hydroxy Stearic Acids (PAHSAs), bioactive lipids with anti-inflammatory and antidiabetic effects, improve systemic and hepatic insulin sensitivity in insulin-resistant mice. PAHSAs augment insulin action on endogenous glucose production (EGP) through direct and indirect actions involving inter-tissue communication between liver and adipose tissue. The direct effect of PAHSAs to inhibit EGP is mediated through a cAMP dependent pathway involving Gα/i protein-coupled receptors. Here, we investigated which receptor mediates PAHSA effects on EGP. We found that 9-PAHSA activates GPR43 in a Ca+2 flux assay. 4-CMTB (0.4μM), a selective agonist-allosteric modulator of GPR43, reduced basal EGP by 23% and glucagon-stimulated EGP by 20% in primary hepatocytes ex vivo. Acute 9-PAHSA treatment (40μM) inhibited basal EGP to the same extent as 4-CMTB. 9-PAHSA suppression of basal EGP was abolished in primary hepatocytes from whole body GPR43 KO mice. Intravenous infusion of 9-PAHSA (9μg/hr) for 3 hrs decreased ambient EGP in chow-fed mice studied 5 hours after food removal (WT: vehicle= 24.2±1.9 vs. PAHSA= 17.2±0.7 mg/kg/min p<0.05). This effect was absent in GPR43 KO mice (KO: vehicle= 25.3±4.2 vs. PAHSA= 23.4±2.7 mg/kg/min). We also examined whether GPR43 activation is required for the direct effect of 9-PAHSA on WAT lipolysis. Treatment with the β-adrenergic agonist isoproterenol increased FFA release from WAT explants by 3.8-fold, and 9-PAHSA inhibited isoproterenol-induced lipolysis by 21% which was similar to the effects of insulin and 4-CMTB. In WAT explants from GPR43 KO mice, 9-PAHSA suppression of isoproterenol-induced FFA release was abolished while insulin still suppressed lipolysis. Sum: 9-PAHSA activates GPR43, which is involved in its direct effects to reduce hepatic glucose production and WAT lipolysis. Conclusion: We have identified a new receptor that mediates some of the beneficial metabolic effects of PAHSAs. Disclosure A. Santoro: None. P. Zhou: None. Y. Zhu: None. O.D. Peroni: None. A.T. Nelson: None. D. Siegel: None. B. Kahn: Advisory Panel; Self; Harrington Discovery Institute, Janssen Pharmaceuticals, Inc., National Institute of Diabetes and Digestive and Kidney Diseases. Funding American Diabetes Association (1-18-PDF-134 to P.Z.); National Institutes of Health (DK43051, DK57521, DK106210, DK112622); JPB Foundation; American Heart Association

Passive exposure to heat improves glucose metabolism in overweight humans.

AimHeat exposure has been indicated to positively affect glucose metabolism. An involvement of heat shock protein 72 (HSP72) in the enhancement of insulin sensitivity upon heat exposure has been previously suggested. Here, we performed an intervention study exploring the effect of passive heat acclimation (PHA) on glucose metabolism and intracellular (a) HSP72 concentrations in overweight humans.MethodsEleven non‐diabetic overweight (BMI 27‐35 kg/m2) participants underwent 10 consecutive days of PHA (4‐6 h/day, 34.4 ± 0.2°C, 22.8 ± 2.7%RH). Before and after PHA, whole‐body insulin sensitivity was assessed using a one‐step hyperinsulinaemic‐euglycaemic clamp, skeletal muscle biopsies were taken to measure intracellular iHSP72, energy expenditure and substrate oxidation were measured using indirect calorimetry and blood samples were drawn to assess markers of metabolic health. Thermophysiological adaptations were measured during a temperature ramp protocol before and after PHA.ResultsDespite a lack of change in iHSP72, 10 days of PHA reduced basal (9.7 ± 1.4 pre‐ vs 8.4 ± 2.1 μmol · kg–1 · min–1 post‐PHA, P = .038) and insulin‐stimulated (2.1 ± 0.9 pre‐ vs 1.5 ± 0.8 μmol · kg–1 · min–1 post‐PHA, P = .005) endogenous glucose production (EGP) and increased insulin suppression of EGP (78.5 ± 9.7% pre‐ vs 83.0 ± 7.9% post‐PHA, P = .028). Consistently, fasting plasma glucose (6.0 ± 0.5 pre‐ vs 5.8 ± 0.4 mmol/L post‐PHA, P = .013) and insulin concentrations (97 ± 55 pre‐ vs 84 ± 49 pmol/L post‐PHA, P = .026) decreased significantly. Moreover, fat oxidation increased, and free fatty acids as well as cholesterol concentrations and mean arterial pressure decreased after PHA.ConclusionOur results show that PHA for 10 days improves glucose metabolism and enhances fat metabolism, without changes in iHSP72. Further exploration of the therapeutic role of heat in cardio‐metabolic disorders should be considered.

MON-LB113 Insulin Resistance in Type 1 Diabetes Managed With Metformin (INTIMET): Rationale and Study Design of a Randomised Placebo-Controlled Trial

Background: Insulin resistance is an under-recognised cardiovascular risk factor in type 1 diabetes (T1D). Individuals with T1D exhibit insulin resistance relative to those without diabetes. In T1D, tissue-specific insulin resistance (muscle, hepatic, adipose) is likely to partly drive increased cardiovascular risk. Adjunctive metformin improves muscle insulin sensitivity in T1D adolescents, but factors that predict responsiveness remain unknown.Objective: To report the rationale and design of the INTIMET study, a double-blind randomised, placebo-controlled trial of metformin in T1D.Methods: Forty adults aged 20-50 years with T1D, and 20 age- gender- and BMI- matched non-diabetic controls will be studied. T1D inclusion criteria are diagnosis > 10 years, HbA1c 9.5% and fasting C-peptide < 0.3nmol/L. Liver and muscle insulin sensitivity will be determined by the 2-stage hyperinsulinemic (20 and 60 mUm2)-euglycemic (5.5 mmol/L) clamp method with deuterated glucose. Subjects with T1D will be randomised to metformin extended-release 1500mg/d or matched placebo for 26 weeks. The primary endpoint is the change in hepatic insulin sensitivity, measured by suppression of endogenous glucose production (EGP) with the low-dose insulin clamp. Secondary endpoints include change in muscle and adipose tissue insulin sensitivity, arterial stiffness, HbA1c, glucose variability, frequency of hypoglycemia, insulin dose, anthropometry, body composition, lipid profile, liver fat and stiffness. Conclusion: The INTIMET study will quantify muscle, liver and adipose insulin-resistance in T1D, determine whether metformin is effective in improving insulin resistance in T1D and identify factors that predict metformin-responsiveness.The trial is registered (Australian New Zealand Clinical Trial Registry, ACTRN12619001440112) and is actively recruiting in Sydney, Australia.

Central KATP Channels Modulate Glucose Effectiveness in Humans and Rodents.

Hyperglycemia is a potent regulator of endogenous glucose production (EGP). Loss of this “glucose effectiveness” is a major contributor to elevated plasma glucose concentrations in type 2 diabetes (T2D). KATP channels in the central nervous system have been shown to regulate EGP in humans and rodents. We examined the contribution of central KATP channels to glucose effectiveness. Under fixed hormonal conditions (studies using a pancreatic clamp), hyperglycemia suppressed EGP by ∼50% in both humans without diabetes and normal Sprague-Dawley rats. By contrast, antagonism of KATP channels with glyburide significantly reduced the EGP-lowering effect of hyperglycemia in both humans and rats. Furthermore, the effects of glyburide on EGP and gluconeogenic enzymes were abolished in rats by intracerebroventricular administration of the KATP channel agonist diazoxide. These findings indicate that about half of the suppression of EGP by hyperglycemia is mediated by central KATP channels. These central mechanisms may offer a novel therapeutic target for improving glycemic control in subjects with T2D.

RBP4 increases lipolysis in human adipocytes and is associated with increased lipolysis and hepatic insulin resistance in obese women.

Retinol‐binding protein‐4 (RBP4) is elevated in serum and adipose tissue (AT) in obesity‐induced insulin resistance and correlates inversely with insulin‐stimulated glucose disposal. But its role in insulin‐mediated suppression of lipolysis, free fatty acids (FFA), and endogenous glucose production (EGP) in humans is unknown. RBP4 mRNA or protein levels were higher in liver, subcutaneous adipose tissue (SAT), and visceral adipose tissue (VAT) in morbidly obese subjects undergoing Roux‐en‐Y gastric bypass surgery compared to lean controls undergoing elective laparoscopic cholecystectomy. RBP4 mRNA expression in SAT correlated with the expression of several macrophage and other inflammation markers. Serum RBP4 levels correlated inversely with glucose disposal and insulin‐mediated suppression of lipolysis, FFA, and EGP. Mechanistically, RBP4 treatment of human adipocytes in vitro directly stimulated basal lipolysis. Treatment of adipocytes with conditioned media from RBP4‐activated macrophages markedly increased basal lipolysis and impaired insulin‐mediated lipolysis suppression. RBP4 treatment of macrophages increased TNFα production. These data suggest that elevated serum or adipose tissue RBP4 levels in morbidly obese subjects may cause hepatic and systemic insulin resistance by stimulating basal lipolysis and by activating macrophages in adipose tissue, resulting in release of pro‐inflammatory cytokines that impair lipolysis suppression. While we have demonstrated this mechanism in human adipocytes in vitro, and correlations from our flux studies in humans strongly support this, further studies are needed to determine whether this mechanism explains RBP4‐induced insulin resistance in humans.

Aerobic exercise training improves hepatic and muscle insulin sensitivity, but reduces splanchnic glucose uptake in obese humans with type 2 diabetes

BackgroundAerobic exercise training is known to have beneficial effects on whole-body glucose metabolism in people with type 2 diabetes (T2D). The responses of the liver to such training are less well understood. The purpose of this study was to determine the effect of aerobic exercise training on splanchnic glucose uptake (SGU) and insulin-mediated suppression of endogenous glucose production (EGP) in obese subjects with T2D.MethodsParticipants included 11 obese humans with T2D, who underwent 15 ± 2 weeks of aerobic exercise training (AEX; n = 6) or remained sedentary for 15 ± 1 weeks (SED; n = 5). After an initial screening visit, each subject underwent an oral glucose load clamp and an isoglycemic/two-step (20 and 40 mU/m2/min) hyperinsulinemic clamp (ISO-clamp) to assess SGU and insulin-mediated suppression of EGP, respectively. After the intervention period, both tests were repeated.ResultsIn AEX, the ability of insulin to suppress EGP was improved during both the low (69 ± 9 and 80 ± 6% suppression; pre-post, respectively; p < 0.05) and high (67 ± 6 and 82 ± 4% suppression, respectively; p < 0.05) insulin infusion periods. Despite markedly improved muscle insulin sensitivity, SGU was reduced in AEX after training (22.9 ± 3.3 and 9.1 ± 6.0 g pre-post in AEX, respectively; p < 0.05).ConclusionsIn obese T2D subjects, exercise training improves whole-body glucose metabolism, in part, by improving insulin-mediated suppression of EGP and enhancing muscle glucose uptake, which occur despite reduced SGU during an oral glucose challenge.

Ethnic differences in intrahepatic lipid and its association with hepatic insulin sensitivity and insulin clearance between men of black and white ethnicity with early type 2 diabetes.

Intrahepatic lipid (IHL) is linked with reduced hepatic insulin sensitivity and insulin clearance. Despite their high risk for type 2 diabetes (T2D), there have been limited investigations of these relationships in black populations. We investigated these relationships in 18 white European (WE) and 18 black West African (BWA) men with T2D <5 years. They underwent magnetic resonance imaging to quantify IHL, a hyperinsulinemic euglycaemic clamp with [6,6 2 H2 ] glucose infusion to assess hepatic insulin sensitivity and a hyperglycaemic clamp to assess insulin clearance. BWA men had lower IHL than WE men (3.7 [5.3] vs 6.6 [10.6]%, P = 0.03). IHL was inversely associated with basal hepatic insulin sensitivity in WE but not BWA men (BWA: r = -0.01, P = 0.96; WE: r = -0.72, P = 0.006) with a significant interaction by ethnicity (Pinteraction = 0.05); however, IHL was not associated with % suppression of endogenous glucose production by insulin in either ethnicity. IHL showed a trend to an association with insulin clearance in BWA only (BWA: r = -0.42, P = 0.09; WE: r = -0.14, P = 0.58). The lack of association between IHL and hepatic insulin sensitivity in BWA men indicates IHL may play a lesser detrimental role in T2D in BWA men.

Non-monotonic dose-response effects of arsenic on glucose metabolism

BackgroundInorganic arsenic (iAs) is a widespread environmental toxin. In addition to being a human carcinogen, its effect on diabetes has started to gain recognition recently. Insulin is the key hormone regulating systemic glucose metabolism. The in vivo effect of iAs on insulin sensitivity has not been directly addressed. ObjectivesHere we use mouse models to dissect the dose-dependent effects of iAs on glucose metabolism in vivo. MethodsWe performed hyperinsulinemic-euglycemic clamp, the gold standard analysis of systemic insulin sensitivity. We also performed dynamic metabolic testings and RNA-seq analysis. ResultsWe found that a low-dose exposure (0.25 ppm iAs in drinking water) caused glucose intolerance in adult male C57BL/6 mice, likely by disrupting glucose-induced insulin secretion without affecting peripheral insulin sensitivity. However, a higher-dose exposure (2.5 ppm iAs) had diminished effects on glucose tolerance despite disrupted pancreatic insulin secretion. Insulin Clamp analysis showed that 2.5 ppm iAs actually enhanced systemic insulin sensitivity by simultaneously enhancing insulin-stimulated glucose uptake in skeletal muscles and improved insulin-mediated suppression of endogenous glucose production. RNA-seq analysis of skeletal muscles revealed that 2.5 ppm iAs regulated expression of many genes involved in the metabolism of fatty acids, pyruvate, and amino acids. ConclusionThese findings suggest that iAs has opposite glycemic effects on distinct metabolic tissues at different dose thresholds. Such non-monotonic dose-response effects of iAs on glucose tolerance shed light on the complex interactions between iAs and the systemic glucose metabolism, which could potentially help reconcile some of the conflicting results in human epidemiological studies.

1777-P: Acute Hyperbaric Oxygen (HBO) Treatment Increases Hepatic Insulin Sensitivity and Muscle Reactive Oxygen Species in Type 2 Diabetes

Diabetes mellitus type 2 (T2D) is characterized by insulin resistance of liver and skeletal muscle, which is at least partly due to impaired muscle mitochondrial function. Long-term HBO therapy, as applied for treating the diabetic foot syndrome, has been shown to improve blood glucose concentrations. To study the underlying mechanisms, we examined the short-term effect of HBO treatment on insulin sensitivity and mitochondrial oxidative capacity and production of reactive oxygen species (ROS) in a randomized, double blinded, placebo-controlled trial. Volunteers with type 2 diabetes (n=4; age 61±4 years; body mass index 30.2±2.2 kg/m2; HbA1c 7.0±0.7%) underwent two 2-hours sessions in a hyperbaric chamber of once with application of 100% oxygen (1.4 bar over atmospheric pressure [barO] for 20 min; HBO) and once with ambient air as placebo (21% oxygen; 1.4 barO; PLC). Tissue-specific insulin sensitivity was assessed by hyperinsulinemic-euglycemic clamps with stable isotope dilution, while muscle oxygen fluxes were measured with high resolution respirometry. After HBO treatment, hepatic insulin sensitivity was higher (insulin-mediated suppression of endogenous glucose production: 69.7±0.1% vs. PLC 55.3±3.2%, p&amp;lt;0.05), whereas peripheral insulin sensitivity was comparable (2.0±0.3 vs. 2.2±0.3 mg*kg-1*min-1, p=0.24). Muscle ROS production markedly increased after HBO (increase in ROS: 73±3% vs. PLC -14±5%; p&amp;lt;0.005), while mitochondrial oxidative capacity only tended to be lower after HBO. In conclusion, a single session of HBO treatment already improves hepatic insulin resistance and stimulates muscle ROS release, which may activate antioxidative defense, both of which could contribute to improved glycaemia upon chronic treatment. Disclosure T. Sarabhai: None. E. Anadol-Schmitz: None. H. Katsuyama: None. D.F. Markgraf: Research Support; Self; Sanofi. L. Busch: None. R. Guthoff: None. J. Schneppendahl: None. M. Roden: Advisory Panel; Self; Boehringer Ingelheim Pharmaceuticals, Inc., Poxel SA, Servier. Board Member; Self; Eli Lilly and Company. Research Support; Self; Boehringer Ingelheim Pharmaceuticals, Inc., Sanofi. Speaker's Bureau; Self; Novo Nordisk Inc.

1831-P: Delayed Glucagon Suppression Contributes to Postprandial Hyperglycemia Independently of the Degree of Insulin Secretion

Type 2 diabetes (T2DM) is characterized by impaired postprandial insulin secretion and glucagon suppression. Recent work suggests that α-cell dysfunction is independent of β-cell dysfunction. The effect of diabetes-associated variation in TCF7L2 on α-cell function also suggests a direct role in the pathogenesis of T2DM. To quantify the interaction between a lack of glucagon suppression with intact, mildly or moderately impaired insulin secretion we studied 45 nondiabetic subjects with and without suppressed glucagon. On both occasions, an intravenous glucose infusion mimicking the systemic appearance of 50g oral glucose was administered in the presence of a pancreatic clamp. Glucagon was infused at a rate of 0.65ng/kg/min, starting at 0 min or 120 min (non-suppressed vs. suppressed respectively). In one group (100%) a nondiabetic insulin profile was infused; another group received 80% of this profile and the third group received 60% of the insulin infused in the first group. We observed that a lack of glucagon suppression increased peak (p &amp;lt; 0.05) and area above basal (AAB) glucose (p &amp;lt; 0.02) in all groups (1.5 ± 0.1 vs. 1.1 ± 0.1; 1.6 ± 0.1 vs. 1.1 ± 0.1; 1.5 ± 0.1 vs.1.3 ± 0.1 Mol per 5hr, 100%, 80%, 60% respectively). These increases were explained by delayed suppression of endogenous glucose production (EGP) so that EGP at 120 minutes was higher (p &amp;lt; 0.05) in the presence of non-suppressed glucagon (6.6 ± 1.0 vs. 4.2 ± 0.6; 7.2 ± 0.8 vs. 5.1 ± 0.5; 7.7 ± 0.8 vs. 5.9 ± 0.6 μmol/kg/min, 100%, 80%, 60% respectively) as was integrated EGP (p &amp;lt; 0.05) over the postprandial period (-1.9 ± 0.4 vs. -2.1 ± 0.1; -1.8 ± 0.1 vs. -1.9 ± 0.2; -1.6 ± 0.3 vs. -1.8 ± 0.1 mmol/kg per 5hr, 100%, 80%, 60% respectively). These data indicate that impaired postprandial glucagon suppression contributes to postprandial hyperglycemia through increased EGP even when insulin secretion is intact as can occur early in prediabetes. These effects are exacerbated by increasing degrees of insulin deficiency. Disclosure J. Adams: None. M.C. Laurenti: Employee; Self; GlySens Incorporated. R.A. Rizza: Advisory Panel; Self; Lilly Diabetes, Metavention, Novo Nordisk A/S, vTv Therapeutics. A.M. Egan: None. C. Cobelli: None. C. Dalla Man: None. A. Vella: Advisory Panel; Self; vTv Therapeutics. Research Support; Self; Novo Nordisk Inc. Funding National Institutes of Health

1893-P: Impact of Lean Hepatic Volume on Hepatic Insulin Resistance in Human NAFLD

Hepatic insulin resistance (H-IR) is a major pathogenesis of type 2 diabetes mellitus (T2DM) with nonalcoholic fatty liver disease (NAFLD). Due to pandemic obesity, in addition to reducing toxic lipids in the liver, searching for other factors that may regulate hepatic insulin sensitivity (H-IS) is inevitable in humans with NAFLD. To find such factors, we performed comprehensive assessment in the patients with NAFLD (n=36) aged 47.4±12.3, BMI 29.4±4.7 kg/m2, DM/non-DM 23/13, HbA1c 6.7±1.0% (mean±SD). We assessed putative biomarkers in blood and urine, body composition, tissue lipid content by 1H-MRS, tissue IS by hyperinsulinemic euglycemic clamp, hepatic histological scores and gene expressions using biopsies, and life styles. Furthermore, we developed a new magnetic resonance imaging analytic method that can exactly evaluate the whole liver volume, whole hepatic lipid volume, and whole hepatic lean volume. We performed single regression analysis between H-IS assessed by clamped % suppression of endogenous glucose production and all evaluated indices. As results, existence of diabetes, fasting plasma glucose, and HbA1c showed significant negative correlation with H-IS, while plasma adiponectin, muscle IS and adipose tissue IS showed significant positive correlation with H-IS. Interestingly, whole liver volume (cm3/m2) and lean hepatic volume (cm3/m2) corrected by body surface area showed negative correlation with H-IS (β=-0.02, -0.03 and p&amp;lt;0.05, &amp;lt;0.01, respectively), specifically in patients with T2DM. Finally, multiple regression analysis confirmed that lean hepatic volume is a negative factor for the H-IS (β=-0.02, p&amp;lt;0.05). Conclusion: Through comprehensive assessment including our new whole hepatic volume evaluation, we first demonstrated that lean hepatic volume strongly associates with H-IR specifically in patients with T2DM. Not only hepatic volume control but quality control supported by adiponectin or other insulin-targeted organs is necessary for H-IS in humans with NAFLD. Disclosure H. Igarashi: None. F. Shigiyama: None. S. Hiruma: None. T. Hirose: None. N. Kumashiro: Speaker's Bureau; Self; Novo Nordisk Inc., Sanofi, Takeda Pharmaceutical Company Limited. Funding Japan Society for the Promotion of Science (26702032, JP17H02180)

140-LB: NGM313, a Novel Activator of b-Klotho/FGFR1c, Improves Insulin Resistance and Reduces Hepatic Fat in Obese, Nondiabetic Subjects

Background: NGM313 is a humanized monoclonal antibody activator of β-klotho/FGFR1c that has been shown to reduce HOMA-IR in obese subjects. This study compared the effects of a single dose of NGM313 vs. daily pioglitazone (PIO) on insulin sensitivity, liver fat content (LFC) and lipids in insulin resistant, obese subjects with increased liver fat. Methods: 25 subjects were randomized 2:1 to either a single dose of NGM313 240 mg SC (n=17) or PIO 45 mg PO QD (n=8) for 36 days. Whole-body insulin sensitivity was determined by a two-step hyperinsulinemic, euglycemic clamp and LFC by magnetic resonance imaging-proton density fat fraction (MRI-PDFF). Results: (Table 1) A single dose of NGM313 significantly increased glucose disposal rate and was comparable to PIO. Suppression of endogenous glucose production was enhanced by both NGM313 and PIO. Significant reductions in LFC, HbA1c, serum triglycerides and LDL-C, and an increase in HDL-C, were observed with NGM313. NGM313 produced a greater reduction in LFC vs. PIO at day 23. The safety and tolerability profile was favorable for both drugs. Conclusion: NGM313 is a potent insulin sensitizer, comparable to PIO. In addition, NGM313 is highly effective in reducing LFC in subjects with increased liver fat. As such, NGM313 has significant potential to be an effective treatment for nonalcoholic steatohepatitis and type 2 diabetes. Disclosure A. DePaoli: Employee; Self; NGM Biopharmaceuticals. V. Phung: Employee; Self; NGM Biopharmaceuticals. Stock/Shareholder; Self; NGM Biopharmaceuticals. M.R. Bashir: Consultant; Self; RadMD. Research Support; Self; Madrigal Pharmaceuticals, Metacrine Inc, NGM Biopharmaceuticals, Pinnacle Clinical Research, ProSciento, Siemens Corporation. L. Morrow: Employee; Spouse/Partner; Eli Lilly and Company. Employee; Self; ProSciento. C. Beysen: None. A. Yan: None. L. Ling: Employee; Self; NGM Biopharmaceuticals. Stock/Shareholder; Self; NGM Biopharmaceuticals. B. Baxter: Employee; Self; NGM Biopharmaceuticals. K.L. Luskey: Consultant; Self; NGM Biopharmaceuticals. J.M. Olefsky: None.

245-OR: Glucose Production and Utilization following Oral Glucose Load in Type 2 Diabetes Patients Treated with Dapagliflozin Alone and in Saxagliptin Combination

Objectives and Methods: To examine changes in endogenous glucose production (EGP). Tissue glucose disappearance (Rd) and urinary glucose excretion (UGE) after SGLT2i alone and combined with DPP-4i. We randomized (2:2:1) 56 T2D patients (A1c=8.9±0.2, FPG=178±10, BMI=34±1.3) to receive dapagliflozin 10 mg [n=22, D], dapagliflozin/saxagliptin 10/5 mg [n=22, D/S], placebo [n=12, P]. Subjects received 75 g OGTT (240 min) with [3H-glu] IV and [14C-glu ] orally pre and post treatment (Tx) for 4 months. Results: Post-Tx, A1c increased by 0.1±0.4% in P and decreased (p&amp;lt;001) by 1.4±0.2% in (D) and 1.9±0.3% in (D/S) (p&amp;lt;0.001). FPG decreased by 44 (D) and 56 (D/S) mg/dl (p &amp;lt;0.001) and was unchanged with (P). During OGTT, increment in PG was reduced by 21 (D) and 29 (D/S) (p&amp;lt;0.001) and increased by 12 mg/dl in (P).Pre-Tx, basal EGP was similar in 3 groups (~2.4 mg/kg.min) and decreased by ~50% during OGTT. Post-Tx, despite the marked decrease in FPG, basal EGP increased in both D and D/S; EGP suppression ~50% during OGTT was unchanged in D and D/S. Pre-Tx, UGE (mg/kg.min) during OGTT was negligible in 3 groups: Post-Tx, UGE increased to 1.0±0.1 (D) and 1.1±0.1 (D/S) (p&amp;lt;0.01) but not in P. Pre-Tx, Tissue Rd (mg/kg.min) increased similarly during OGTT in all 3 groups by ~ 40%; Post-Tx, the increase in Tissue Rd was greater (p&amp;lt;0.05) in D (∆1.7±0.3) and D/P (∆3.8±0.3) vs. P (∆1.4±0.2). Pre-Tx, basal glucose clearance (GC) was similar in all 3 groups (~1.4 ml/kg.min) and did not change during OGTT. Post-Tx, both basal GC and GC during OGTT increased (p&amp;lt;0.05-0.01) in D and D/S, without change in plasma insulin/C-peptide conc. Conclusions: D and D/S treatment improved glycemic control by (i) increasing UGE and (ii) augmenting Tissue glucose clearance by ameliorating glucotoxicity, Saxa addition to dapa produced only modest further A1c reduction because it failed to block dapagliflozin-induced stimulation of EGP, even though it increased insulin and decreased glucagon secretion. Disclosure Y. Qin: None. A. Gastaldelli: Consultant; Self; A. Menarini Diagnostics, Eli Lilly and Company, Genentech, Inc., Gilead Sciences, Inc., Inventiva Pharma. M. Abdul-Ghani: None. J.M. Adams: None. A.M. Ali: None. M.M. Eletrebi: None. R.A. Martinez: None. C.L. Triplitt: Consultant; Self; Abbott. Speaker's Bureau; Self; AstraZeneca, Boehringer Ingelheim Pharmaceuticals, Inc., Eli Lilly and Company, Janssen Pharmaceuticals, Inc. R.A. DeFronzo: Advisory Panel; Self; AstraZeneca, Boehringer Ingelheim Pharmaceuticals, Inc., Elcelyx Therapeutics, Inc., Intarcia Therapeutics, Inc., Janssen Pharmaceuticals, Inc., Novo Nordisk Inc. Research Support; Self; AstraZeneca, Boehringer Ingelheim Pharmaceuticals, Inc., Janssen Pharmaceuticals, Inc., Merck &amp; Co., Inc. Speaker&amp;s Bureau; Self; AstraZeneca, Novo Nordisk Inc. E. Cersosimo: None. Funding AstraZeneca

227-OR: Novel Method of Assessing Hypothalamic KATP Channel Activation in Humans Using Magnetic Resonance Imaging (MRI)

Hypothalamic KATP channels play an important role in regulating metabolism: activation of these channels with diazoxide (DZX) reduces endogenous glucose production (EGP) in rodents. When insulin is maintained at basal levels, oral DZX similarly suppresses EGP in humans (JCI 121:4916, 2011). Given the need to directly examine central regulation of EGP in humans, we developed a novel non-invasive measure of hypothalamic KATP channel activation. Since cerebral blood flow (CBF) and neuronal activity are coupled, we mapped hypothalamic neuronal activity using pseudo-continuous arterial spin labeling (pCASL) to measure CBF using 3 Tesla MRI with high resolution 3-dimensional (3D) acquisition and published analyses approaches (MRM 73: 102, 2015). The hypothalamus was extracted from each 3D map (3x3x3mm) using a hypothalamus region-of-interest (ROI) mask delineated upon the Johns Hopkins Template. To directly assess hypothalamic KATP channel activity using pCASL, we examined the time dependent effects of DZX (6mg/kg) vs. placebo in a randomized, double blinded fashion. Eight healthy nondiabetic individuals (42±4 yr, BMI 24±1 kg/m2, 7M) underwent a baseline scan, with repeat scans at 2.5 and 5 hours following DZX or placebo. This time course was determined based on previous observations that DZX appearance in rat CSF precedes EGP suppression, which is maximal at ∼6 hours in rats and humans. DZX induced an ∼11% drop in hypothalamic CBF, from 59.5±2.5 to 53.0±3.1 ml/100g/min at 2.5 hours (p=0.06), returning to baseline at 5 hours (57.7±2.7 ml/100g/min, p=0.3). Following placebo there was no change in CBF (p=0.8 by repeated measures ANOVA). No change in CBF was observed in other brain regions (e.g., cerebral cortex, thalamus, or hippocampus). In conclusion, pCASL provides a novel image-based measure of hypothalamic response to KATP channel activation in vivo, and can thus be used to examine the metabolic significance of hypothalamic KATP channel activation in humans. Disclosure S. Sharma: None. S. Aleksic: None. R. Maginley: None. E. Lontchi Yimagou: None. L. Upadhyay: None. S. Bhansali: None. O. Sandu: None. C.A. Branch: None. M. Hawkins: Other Relationship; Self; Novo Nordisk Inc. Funding National Institutes of Health (R01DK069861); Albert Einstein College of Medicine

Modest changes to glycemic regulation are sufficient to maintain glucose fluxes in healthy young men following overfeeding with a habitual macronutrient composition

Currently, it is unclear whether short-term overfeeding in healthy people significantly affects postprandial glucose regulation, as most human overfeeding studies have utilized induced experimental conditions such as the euglycemic-hyperinsulinemic clamp technique to assess glucoregulation. The aim of this study was to quantify glucose fluxes [rates of meal glucose appearance (Ra), disposal (Rd), and endogenous glucose production (EGP)] in response to 5 and 28 days of overfeeding (+45% energy) while maintaining habitual macronutrient composition (31.0 ± 1.9% fat, 48.6 ± 2.2% carbohydrate, 16.7 ± 1.4% protein) in healthy, lean young men. Meal tolerance testing was combined with the triple-stable isotope glucose tracer approach. Visceral adipose volume increased by ~15% with 5 days of overfeeding, while there was no further change at 28 days. In contrast, body mass (+1.6 kg) and fat mass (+1.3 kg) were significantly increased only after 28 days of overfeeding. Fasting EGP, Rd, and insulin were increased at 5 but unchanged after 28 days. Postprandial glucose and insulin responses were unaltered by 5 days of overfeeding but were modestly increased after 28 days (P < 0.05). However, meal Ra and glucose Rd were significantly increased after both 5 and 28 days of overfeeding (P < 0.05). Despite this, overfeeding did not lead to alterations to postprandial EGP suppression. Thus, in contrast to findings from euglycemic-hyperinsulinemic clamp studies, chronic overfeeding did not affect the ability to suppress EGP or stimulate Rd under postprandial conditions. Rather, glucose flux was appropriately maintained following 28 days of overfeeding through modest increases in postprandial glycemia and insulinemia.

Impact of Brain Fatty Acid Signaling on Peripheral Insulin Action in Mice.

Glucose homeostasis and energy balance are under control by peripheral and brain processes. Especially insulin signaling in the brain seems to impact whole body glucose homeostasis and interacts with fatty acid signaling. In humans circulating saturated fatty acids are negatively associated with brain insulin action while animal studies suggest both positive and negative interactions of fatty acids and insulin brain action. This apparent discrepancy might reflect a difference between acute and chronic fatty acid signaling. To address this question we investigated the acute effect of an intracerebroventricular palmitic acid administration on peripheral glucose homeostasis. We developed and implemented a method for simultaneous monitoring of brain activity and peripheral insulin action in freely moving mice by combining radiotelemetry electrocorticography (ECoG) and euglycemic-hyperinsulinemic clamps. This method allowed gaining insight in the early kinetics of brain fatty acid signaling and its contemporaneous effect on liver function in vivo, which, to our knowledge, has not been assessed so far in mice. Insulin-induced brain activity in the theta and beta band was decreased by acute intracerebroventricular application of palmitic acid. Peripherally it amplified insulin action as demonstrated by a significant inhibition of endogenous glucose production and increased glucose infusion rate. Moreover, our results further revealed that the brain effect of peripheral insulin is modulated by palmitic acid load in the brain. These findings suggest that insulin action is amplified in the periphery and attenuated in the brain by acute palmitic acid application. Thus, our results indicate that acute palmitic acid signaling in the brain may be different from chronic effects.