Role of Glycosuria in SGLT2 Inhibitor-Induced Cardiorenal Protection: A Mechanistic Analysis of the CREDENCE Trial.

SGLT2 inhibitors have been shown to provide pronounced reductions in cardiorenal outcomes, including cardiovascular death, heart failure, and renal failure. The mechanisms underlying these benefits remain uncertain. We hypothesized that the effects could be attributed to the elevated glycosuria induced by these drugs. Urine concentrations of glucose, creatinine, and ketones were measured at baseline and after 1 year of treatment with either placebo or canagliflozin 100 mg/day, in approximately 2,600 individuals from the Canagliflozin and Renal Events in Diabetes with Established Nephropathy Clinical Evaluation (CREDENCE) trial (enrolling patients with type 2 diabetes, chronic kidney disease (CKD), and albuminuria). Associations between glycosuria and the primary composite end point from CREDENCE, and secondary outcomes were assessed using Cox proportional hazards models. Canagliflozin treatment increased fractional urinary glucose excretion (± SD) from 3 ± 9% at baseline to 30 ± 26% at year 1 (vs. 5 ± 19% with placebo; P < 0.001). Patients in the canagliflozin arm and in the top quartile of urine glucose to creatinine ratio at year 1 were significantly protected for the primary end point (hazard ratio [HR] 0.42; 95% CI 0.30-0.61); similar results were seen for cases of hospitalized heart failure (HR 0.45; 95% CI 0.27-0.73) and all-cause death (HR 0.56; 95% CI 0.39-0.80). These associations persisted when adjustments were made for multiple conventional risk factors. Among patients with type 2 diabetes and CKD treated with canagliflozin, individuals with the highest glycosuria levels had the strongest protection against multiple cardiorenal outcomes.

A long-acting GDF15 analog causes robust, sustained weight loss and reduction of food intake in an obese nonhuman primate model.

Growth Differentiation Factor-15 (GDF15) is a circulating polypeptide linked to cellular stress and metabolic adaptation. GDF15's half-life is ~3 h and activates the glial cell line-derived neurotrophic factor family receptor alpha-like (GFRAL) receptor expressed in the area postrema. To characterize sustained GFRAL agonism on food intake (FI) and body weight (BW), we tested a half-life extended analog of GDF15 (Compound H [CpdH]) suitable for reduced dosing frequency in obese cynomolgus monkeys. Animals were chronically treated once weekly (q.w.) with CpdH or long-acting GLP-1 analog dulaglutide. Mechanism-based longitudinal exposure-response modeling characterized effects of CpdH and dulaglutide on FI and BW. The novel model accounts for both acute, exposure-dependent effects reducing FI and compensatory changes in energy expenditure (EE) and FI occurring over time with weight loss. CpdH had linear, dose-proportional pharmacokinetics (terminal half-life ~8 days) and treatment caused exposure-dependent reductions in FI and BW. The 1.6 mg/kg CpdH reduced mean FI by 57.5% at 1 week and sustained FI reductions of 31.5% from weeks 9-12, resulting in peak reduction in BW of 16 ± 5%. Dulaglutide had more modest effects on FI and peak BW loss was 3.8 ± 4.0%. Longitudinal modeling of both the FI and BW profiles suggested reductions in BW observed with both CpdH and dulaglutide were fully explained by exposure-dependent reductions in FI without increase in EE. Upon verification of the pharmacokinetic/pharmacodynamic relationship established in monkeys and humans for dulaglutide, we predicted that CpdH could reach double digit BW loss in humans. In summary, a long-acting GDF15 analog led to sustained reductions in FI in overweight monkeys and holds potential for effective clinical obesity pharmacotherapy.

Validation of a diet-induced Macaca fascicularis model of non-alcoholic steatohepatitis with dietary and pioglitazone interventions.

AIM: To develop an obese, insulin-resistant cynomolgus monkey model of non-alcoholic steatohepatitis (NASH) with fibrosis with a high fat/high cholesterol (HFHC) diet (with or without high fructose) and test its responsiveness to caloric restriction or pioglitazone. METHODS: First, two groups of monkeys (n = 24/group) with histologically proven NASH and fibrosis were fed the HFHC diet for 17 weeks. The treatment group was subjected to a 40% caloric restriction (CR) and had their diet switched from the HFHC diet to a chow diet (DSCR). Paired liver biopsies were taken before and 17 weeks after DSCR. Subsets of monkeys (nine/group) had whole liver fat content assessed by MRI. Next, two groups of monkeys with histologically proven NASH and fibrosis were treated with vehicle (n = 9) or pioglitazone (n = 20) over 24 weeks. RESULTS: The HFHC and DSCR groups lost 0.9% and 11.4% of body weight, respectively. After 17 weeks, non-alcoholic fatty liver disease activity score (NAS) improvement was observed in 66.7% of the DSCR group versus 12.5% of the HFHC group (P < .001). Hepatic fat was reduced to 5.2% in the DSCR group versus 23.0% in the HFHC group (P = .0001). After 24 weeks, NAS improvement was seen in 30% of the pioglitazone group versus 0% of the vehicle group (P = .08). CONCLUSIONS: Both weight loss induced by DSCR and treatment with pioglitazone improve the histological features of NASH in a diet-induced cynomolgus monkey model. This model provides a translational preclinical model for testing novel NASH therapies.

Drug Development in Kidney Disease: Proceedings From a Multistakeholder Conference.

Occasional bursts of discovery and innovation have appeared during the otherwise stagnant past several decades of drug development in nephrology. Among other recent drug discoveries, the unexpected kidney benefits observed with sodium/glucose cotransporter 2 inhibitors may herald a renaissance of drug development in kidney disease. This recent progress highlights the need to further promote and stimulate research and development of promising therapies that may ameliorate the morbidity and mortality associated with kidney disease. To help identify and address barriers to drug development in nephrology, the Duke Clinical Research Institute convened a conference in April 2019 that included stakeholders from academia, industry, government agencies, and patient advocacy. From these discussions, several opportunities were identified to improve every stage of drug development for kidney disease from early discovery to implementation into practice. Key topics reviewed in this article are the utility of interconnected data and site research networks, surrogate end points, pragmatic and adaptive trial designs, the promising uses of real-world data, and methods to improve the generalizability of trial results and uptake of approved drugs for kidney-related diseases.

Intrahepatic fat, irrespective of ethnicity, is associated with reduced endogenous insulin clearance and hepatic insulin resistance in obese youths: A cross-sectional and longitudinal study from the Yale Pediatric NAFLD cohort.

AIM: To evaluate whether intrahepatic fat accumulation contributes to impaired insulin clearance and hepatic insulin resistance across different ethnic groups. METHODS: The intrahepatic fat content (HFF%) was quantified by magnetic resonance imaging in a multi-ethnic cohort of 632 obese youths aged 7-18 years at baseline and after a 2-year follow-up. Insulin secretion rate (ISR), endogenous insulin clearance (EIC) and hepatic insulin resistance index (HIRI) were estimated by modelling glucose, insulin and C-peptide data during 3-hour, 9-point oral glucose tolerance tests. RESULTS: African American youths exhibited the lowest HFF% and a prevalence of non-alcoholic fatty liver disease (NAFLD) less than half of that shown by Caucasians and Hispanics. Furthermore, African Americans had lower EIC and glucose-stimulated ISR, despite similar HIRI and plasma insulin levels, compared with Caucasians and Hispanics. EIC and HIRI were markedly reduced in individuals with NAFLD and declined across group-specific HFF% tertiles in all ethnic groups. Consistently, the HFF% correlated with EIC and HIRI, irrespective of the ethnic background, after adjustment for age, sex, ethnicity, adiposity, waist-hip ratio, pubertal status and plasma glucose levels. An increased HFF% at follow-up was associated with decreased EIC and increased HIRI across all groups. CONCLUSIONS: Intrahepatic lipid accumulation is associated with reduced insulin clearance and hepatic insulin sensitivity in obese youths, irrespective of their ethnic background.

Influence of adiposity, insulin resistance, and intrahepatic triglyceride content on insulin kinetics.

BACKGROUNDInsulin is a key regulator of metabolic function. The effects of excess adiposity, insulin resistance, and hepatic steatosis on the complex integration of insulin secretion and hepatic and extrahepatic tissue extraction are not clear.METHODSA hyperinsulinemic-euglycemic clamp and a 3-hour oral glucose tolerance test were performed to evaluate insulin sensitivity and insulin kinetics after glucose ingestion in 3 groups: (a) lean subjects with normal intrahepatic triglyceride (IHTG) and glucose tolerance (lean-NL; n = 14), (b) obese subjects with normal IHTG and glucose tolerance (obese-NL; n = 24), and (c) obese subjects with nonalcoholic fatty liver disease (NAFLD) and prediabetes (obese-NAFLD; n = 22).RESULTSInsulin sensitivity progressively decreased and insulin secretion progressively increased from the lean-NL to the obese-NL to the obese-NAFLD groups. Fractional hepatic insulin extraction progressively decreased from the lean-NL to the obese-NL to the obese-NAFLD groups, whereas total hepatic insulin extraction (molar amount removed) was greater in the obese-NL and obese-NAFLD subjects than in the lean-NL subjects. Insulin appearance in the systemic circulation and extrahepatic insulin extraction progressively increased from the lean-NL to the obese-NL to the obese-NAFLD groups. Total hepatic insulin extraction plateaued at high rates of insulin delivery, whereas the relationship between systemic insulin appearance and total extrahepatic extraction was linear.CONCLUSIONHyperinsulinemia after glucose ingestion in obese-NL and obese-NAFLD is due to an increase in insulin secretion, without a decrease in total hepatic or extrahepatic insulin extraction. However, the liver's maximum capacity to remove insulin is limited because of a saturable extraction process. The increase in insulin delivery to the liver and extrahepatic tissues in obese-NAFLD is unable to compensate for the increase in insulin resistance, resulting in impaired glucose homeostasis.TRIAL REGISTRATIONClinicalTrials.gov NCT02706262.FUNDINGNIH grants DK56341 (Nutrition Obesity Research Center), DK052574 (Digestive Disease Research Center), RR024992 (Clinical and Translational Science Award), and T32 DK007120 (a T32 Ruth L. Kirschstein National Research Service Award); the American Diabetes Foundation (1-18-ICTS-119); Janssen Research & Development; and the Pershing Square Foundation.

Lower Insulin Clearance Parallels a Reduced Insulin Sensitivity in Obese Youths and Is Associated With a Decline in ß-Cell Function Over Time.

We examined the relationship between insulin clearance, insulin sensitivity, and ß-cell function and the longitudinal effect of insulin clearance on ß-cell function in lean and obese insulin-sensitive and insulin-resistant adolescents. A hyperinsulinemic-euglycemic and a hyperglycemic clamp were performed in 110 youths to quantify hepatic and peripheral clearance, insulin sensitivity, and ß-cell function (disposition index, DIh-clamp). Participants underwent an oral glucose tolerance test at baseline and after 2 years to assess glucose tolerance and oral ß-cell function (oDIcpep) and were sorted into four groups (lean and obese normal glucose tolerance, insulin sensitive, insulin resistant, and impaired glucose tolerance). Insulin sensitivity was defined based on the median of insulin stimulated glucose disposal (M) measured during the hyperinsulinemic-euglycemic clamp. Lean and obese insulin-sensitive participants did not differ with respect to hepatic and peripheral clearance or for insulin sensitivity. Insulin sensitivity was linearly correlated with whole-body insulin clearance. Hepatic insulin extraction at baseline acted as an independent determinant of ß-cell function at follow-up. The decline in insulin sensitivity, even in the absence of an impairment of glucose tolerance, is associated with lowering of hepatic insulin clearance in obese youth, which in turn may contribute to the decline in ß-cell function over time.

Effect of canagliflozin treatment on hepatic triglyceride content and glucose metabolism in patients with type 2 diabetes.

AIM: To evaluate the impact of the sodium glucose co-transporter 2 inhibitor canagliflozin on intrahepatic triglyceride (IHTG) accumulation and its relationship to changes in body weight and glucose metabolism. MATERIALS AND METHODS: In this double-blind, parallel-group, placebo-controlled, 24-week trial subjects with inadequately controlled type 2 diabetes mellitus (T2DM; HbA1c = 7.7% ± 0.7%) from two centres were randomly assigned (1:1) to canagliflozin 300 mg or placebo. We measured IHTG by proton-magnetic resonance spectroscopy (primary outcome), hepatic/muscle/adipose tissue insulin sensitivity during a 2-step euglycaemic insulin clamp, and beta-cell function during a mixed meal tolerance test. Analyses were per protocol. RESULTS: Between 8 September 2014-13 June 2016, 56 patients were enrolled. Canagliflozin reduced HbA1c (placebo-subtracted change: -0.71% [-1.08; -0.33]) and body weight (-3.4% [-5.4; -1.4]; both P ≤ 0.001). A numerically larger absolute decrease in IHTG occurred with canagliflozin (-4.6% [-6.4; -2.7]) versus placebo (-2.4% [-4.2; -0.6]; P = 0.09). In patients with non-alcoholic fatty liver disease (n = 37), the decrease in IHTG was -6.9% (-9.5; -4.2) versus -3.8% (-6.3; -1.3; P = 0.05), and strongly correlated with the magnitude of weight loss (r = 0.69, P < 0.001). Body weight loss ≥5% with a ≥30% relative reduction in IHTG occurred more often with canagliflozin (38% vs. 7%, P = 0.009). Hepatic insulin sensitivity improved with canagliflozin (P < 0.01), but not muscle or adipose tissue insulin sensitivity. Beta-cell glucose sensitivity, insulin clearance, and disposition index improved more with canagliflozin (P < 0.05). CONCLUSIONS: Canagliflozin improves hepatic insulin sensitivity and insulin secretion and clearance in patients with T2DM. IHTG decreases in proportion to the magnitude of body weight loss, which tended to be greater and occur more often with canagliflozin.

Hepatic Insulin Extraction in NAFLD Is Related to Insulin Resistance Rather Than Liver Fat Content.

CONTEXT: Total insulin clearance is decreased in nonalcoholic fatty liver disease (NAFLD), but the relationship between liver fat and hepatic insulin extraction (HIE) is unknown. OBJECTIVE: This cross-sectional study addresses the hypothesis that HIE is reduced in NAFLD and investigates metabolic and/or anthropometric characteristics most closely associated with insulin clearance. PARTICIPANTS: Nondiabetic subjects with NAFLD (n = 13) and age- and body mass index (BMI)-matched controls with normal liver enzymes (n = 15) underwent abdominal CT, dual-energy X-ray absorptiometry, oral glucose tolerance test (OGTT), and labeled two-step hyperinsulinemic-euglycemic clamps. OUTCOME MEASUREMENTS: Liver fat was estimated by the CT liver/spleen ratio. Hepatic and extrahepatic insulin clearances were modeled using clamp and OGTT data. RESULTS: Extrahepatic insulin clearance and HIE were not different between NAFLD and controls and did not correlate with liver fat. HIE was positively correlated with insulin sensitivity [rate of glucose disposal (Rd; low r = +0.7, P < 0.001; high r = +0.6, P = 0.001), adiponectin (r = +0.55, P = 0.004), and insulin-mediated suppression of clamp nonesterified free fatty acid (NEFA; r = +0.67, P < 0.001)] but was not associated with fasting NEFA, insulin-mediated suppression of glucose production, or measures of adiposity. Extrahepatic insulin clearance was positively associated with percent body fat (r = +0.44, P = 0.02) and subcutaneous fat (r = +0.42, P = 0.03) but not BMI, intra-abdominal fat, liver fat, Rd, adiponectin, or NEFA. CONCLUSIONS: HIE is not directly associated with hepatic steatosis but is associated with muscle and adipose tissue insulin resistance. The data suggest differential regulation of insulin clearance with extrahepatic insulin clearance being associated with body fat and not insulin sensitivity.

Dissection of hepatic versus extra-hepatic insulin clearance: Ethnic differences in childhood.

AIMS: Adult African American (AA) women have one third of the hepatic insulin clearance of European American (EA) women. This lower hepatic (but not extra-hepatic) insulin clearance in AA individuals is associated with higher plasma insulin concentrations. This study aims to understand whether impairment of hepatic insulin clearance is seen in AA individuals since childhood, possibly suggesting that genetic/epigenetic factors, rather than lifestyle only, contribute to this. MATERIALS AND METHODS: A total of 203 children (105 male and 98 female (55 AA, 88 EA and 60 Hispanic American [HA]; ages, 7-13 years; mean BMI, 19 kg/m2 )) underwent the frequently applied intravenous glucose tolerance test (FSIGT) at the University of Alabama at Birmingham, General Clinical Research Center and Department of Nutrition Sciences. Glucose, insulin and C-peptide levels were measured and hepatic and extra-hepatic insulin clearances were calculated using mathematical modelling. RESULTS: Fractional hepatic insulin extraction (FEL ) was lower in AA than in EA children (mean (SD), 19% (20%) vs 33% (20%); P = 0.0007). Adjusting for age, Tanner stage and body fat, FEL was lower in AA than in EA children (P = 0.0012), and there was a slight sex-related difference (FEL, 24% (10%) vs 29% (10%) in boys vs girls; P = 0.04). Extra-hepatic insulin clearance did not differ with ethnicity (27 (12), 21 (12) and 24 (28) mL/kg/min for AA, HA and EA children, respectively; P > 0.05). CONCLUSIONS: At a young age, FEL is lower in AAs than in EAs, which does not rule out genetic/epigenetic factors. These differences are related to hyperinsulinaemia and, over time, could possibly contribute to metabolic disorders in AA individuals.

Potent Sodium/Glucose Cotransporter SGLT1/2 Dual Inhibition Improves Glycemic Control Without Marked Gastrointestinal Adaptation or Colonic Microbiota Changes in Rodents.

The sodium/glucose cotransporters (SGLT1 and SGLT2) transport glucose across the intestinal brush border and kidney tubule. Dual SGLT1/2 inhibition could reduce hyperglycemia more than SGLT2-selective inhibition in patients with type 2 diabetes. However, questions remain about altered gastrointestinal (GI) luminal glucose and tolerability, and this was evaluated in slc5a1-/- mice or with a potent dual inhibitor (compound 8; SGLT1 Ki = 1.5 ± 0.5 nM 100-fold greater potency than phlorizin; SGLT2 Ki = 0.4 ± 0.2 nM). 13C6-glucose uptake was quantified in slc5a1-/- mice and in isolated rat jejunum. Urinary glucose excretion (UGE), blood glucose (Sprague-Dawley rats), glucagon-like peptide 1 (GLP-1), and hemoglobin A1c (HbA1c) levels (Zucker diabetic fatty rats) were measured. Intestinal adaptation and rRNA gene sequencing was analyzed in C57Bl/6 mice. The blood 13C6-glucose area under the curve (AUC) was reduced in the absence of SGLT1 by 75% (245 ± 6 vs. 64 ± 6 mg/dl⋅h in wild-type vs. slc5a1-/- mice) and compound 8 inhibited its transport up to 50% in isolated rat jejunum. Compound 8 reduced glucose excursion more than SGLT2-selective inhibition (e.g., AUC = 129 ± 3 vs. 249 ± 5 mg/dl⋅h for 1 mg/kg compound 8 vs. dapagliflozin) with similar UGE but a lower renal glucose excretion threshold. In Zucker diabetic fatty rats, compound 8 decreased HbA1c and increased total GLP-1 without changes in jejunum SGLT1 expression, mucosal weight, or villus length. Overall, compound 8 (1 mg/kg for 6 days) did not increase cecal glucose concentrations or bacterial diversity in C57BL/6 mice. In conclusion, potent dual SGLT1/2 inhibition lowers blood glucose by reducing intestinal glucose absorption and the renal glucose threshold but minimally impacts the intestinal mucosa or luminal microbiota in chow-fed rodents.

Intra- and inter-subject variability for increases in serum ketone bodies in patients with type 2 diabetes treated with the sodium glucose co-transporter 2 inhibitor canagliflozin.

Sodium glucose co-transporter 2 (SGLT2) inhibitors have been associated with increased serum ketone body levels in patients with type 2 diabetes mellitus (T2DM). In the present analysis we evaluated serum ketone body levels and variability in 1278 Japanese patients with T2DM treated with canagliflozin 100 or 200 mg. Similar mean increases in ketone body concentrations of ~2-fold were seen with both canagliflozin doses. The median (interquartile range) percent change from baseline was 62% (0;180) for acetoacetate and 78% (2;236) for ß-hydroxybutyrate. Approximately two-thirds of the variability in each ketone measure was attributed to intra-subject variability. Intra-subject variability was higher for serum ketones than other metabolites. Patients in the lowest response tertile exhibited no increase in ketones. Those in the highest response tertile tended to be male and have higher fasting plasma glucose levels, lower insulin levels, and longer T2DM duration at baseline. Moreover, changes in serum ketones were not fully explained by changes in plasma fatty acids, suggesting downstream effects of SGLT2 inhibition on hepatic metabolism that favour ketogenesis. In summary, increases in serum ketone bodies with canagliflozin were greater and more variable than changes in other metabolic measures in Japanese patients with T2DM.

Pharmacokinetics and pharmacodynamics of canagliflozin in pediatric patients with type 2 diabetes.

OBJECTIVE: Canagliflozin, a sodium glucose cotransporter 2 inhibitor approved for the treatment of adults with type 2 diabetes (T2D), increases urinary glucose excretion (UGE) and lowers plasma glucose (PG) levels by reducing the renal threshold for glucose (RTG ). This study assessed the pharmacokinetics (PK) and pharmacodynamics (PD) of canagliflozin in pediatric T2D patients. METHODS: Patients, aged 10 to 17 years with mean weight 107.2 kg and body mass index 38.2 kg/m2 , underwent PK and PD assessments after receiving a single daily dose of canagliflozin 100 mg (n = 8) or 300 mg (n = 9) for 14 days. Data are presented as mean (SD). RESULTS: There were dose-dependent increases in the PK of canagliflozin 100 and 300 mg, with maximum plasma concentrations and areas under plasma concentration curves that were similar to the corresponding values in adults. Mean 24-hour RTG fell to 84.6 (13.8) mg/dL with canagliflozin 100 mg and to 69.1 (9.6) mg/dL with canagliflozin 300 mg; also consistent with reductions in RTG in adults. Mean 24-hour UGE increased from 5.3 (10.5) g at baseline to 74.1 (37.4) g with canagliflozin 100 mg and from 0.1 (0.04) g to 68.6 (26.5) g with canagliflozin 300 mg. Both doses were well tolerated and the tablets had acceptable taste, smell, and swallowability. CONCLUSIONS: In pediatric T2D patients, canagliflozin 100 and 300 mg had PK and PD characteristics similar to those in adults with T2D, which is likely due to the relative maturity and increased body weight of youth affected with this disorder.

Hepatic but Not Extrahepatic Insulin Clearance Is Lower in African American Than in European American Women.

African Americans (AAs) tend to have higher plasma insulin concentrations than European Americans (EAs); the increased insulin concentrations have been attributed to increased secretion and/or decreased insulin clearance by liver or other tissues. This work characterizes the contributions of hepatic versus extrahepatic insulin degradation related to ethnic differences between AAs and EAs. By using a recently developed mathematical model that uses insulin and C-peptide measurements from the insulin-modified, frequently sampled intravenous glucose tolerance test (FSIGT), we estimated hepatic versus extrahepatic insulin clearance in 29 EA and 18 AA healthy women. During the first 20 min of the FSIGT, plasma insulin was approximately twice as high in AAs as in EAs. In contrast, insulin was similar in AAs and EAs after the 20-25 min intravenous insulin infusion. Hepatic insulin first-pass extraction was two-thirds lower in AAs versus EAs in the overnight-fasted state. In contrast, extrahepatic insulin clearance was not lower in AAs than in EAs. The difference in insulin degradation between AAs and EAs can be attributed totally to liver clearance. The mechanism underlying reduced insulin degradation in AAs remains to be clarified, as does the relative importance of reduced liver clearance to increased risk for type 2 diabetes.

Dynamic population pharmacokinetic-pharmacodynamic modelling and simulation supports similar efficacy in glycosylated haemoglobin response with once or twice-daily dosing of canagliflozin.

AIM: Canagliflozin is an SGLT2 inhibitor approved for the treatment of type-2 diabetes. A dynamic population pharmacokinetic-pharmacodynamic (PK/PD) model relating 24-h canagliflozin exposure profiles to effects on glycosylated haemoglobin was developed to compare the efficacy of once-daily and twice-daily dosing. METHODS: Data from two clinical studies, one with once-daily, and the other with twice-daily dosing of canagliflozin as add-on to metformin were used (n = 1347). An established population PK model was used to predict full 24-h profiles from measured trough concentrations and/or baseline covariates. The dynamic PK/PD model incorporated an Emax relationship between 24-h canagliflozin exposure and HbA1c-lowering with baseline HbA1c affecting the efficacy. RESULTS: Internal and external model validation demonstrated that the model adequately predicted HbA1c-lowering for canagliflozin once-daily and twice-daily dosing regimens. The differences in HbA1c reduction between the twice-daily and daily mean profiles were minimal (at most 0.023% for 100 mg total daily dose [TDD] and 0.011% for 300 mg TDD, up to week 26, increasing with time and decreasing with TDD) and not considered clinically meaningful. CONCLUSIONS: Simulations using this model demonstrated the absence of clinically meaningful between-regimen differences in efficacy, supported the regulatory approval of a canagliflozin-metformin immediate release fixed-dose combination tablet and alleviated the need for an additional clinical study.

How Strongly Does Appetite Counter Weight Loss? Quantification of the Feedback Control of Human Energy Intake.

OBJECTIVE: To quantify the feedback control of energy intake in response to long-term covert manipulation of energy balance in free-living humans. METHODS: A validated mathematical method was used to calculate energy intake changes during a 52-week placebo-controlled trial in 153 patients treated with canagliflozin, a sodium glucose co-transporter inhibitor that increases urinary glucose excretion, thereby resulting in weight loss without patients being directly aware of the energy deficit. The relationship between the body weight time course and the calculated energy intake changes was analyzed using principles from engineering control theory. RESULTS: It was discovered that weight loss leads to a proportional increase in appetite resulting in eating above baseline by ∼100 kcal/day per kilogram of lost weight-an amount more than threefold larger than the corresponding energy expenditure adaptations. CONCLUSIONS: While energy expenditure adaptations have often been considered the main reason for slowing of weight loss and subsequent regain, feedback control of energy intake plays an even larger role and helps explain why long-term maintenance of a reduced body weight is so difficult.

Standardized Mixed-Meal Tolerance and Arginine Stimulation Tests Provide Reproducible and Complementary Measures of ß-Cell Function: Results From the Foundation for the National Institutes of Health Biomarkers Consortium Investigative Series.

OBJECTIVE: Standardized, reproducible, and feasible quantification of ß-cell function (BCF) is necessary for the evaluation of interventions to improve insulin secretion and important for comparison across studies. We therefore characterized the responses to, and reproducibility of, standardized methods of in vivo BCF across different glucose tolerance states. RESEARCH DESIGN AND METHODS: Participants classified as having normal glucose tolerance (NGT; n = 23), prediabetes (PDM; n = 17), and type 2 diabetes mellitus (T2DM; n = 22) underwent two standardized mixed-meal tolerance tests (MMTT) and two standardized arginine stimulation tests (AST) in a test-retest paradigm and one frequently sampled intravenous glucose tolerance test (FSIGT). RESULTS: From the MMTT, insulin secretion in T2DM was >86% lower compared with NGT or PDM (P < 0.001). Insulin sensitivity (Si) decreased from NGT to PDM (∼50%) to T2DM (93% lower [P < 0.001]). In the AST, insulin secretory response to arginine at basal glucose and during hyperglycemia was lower in T2DM compared with NGT and PDM (>58%; all P < 0.001). FSIGT showed decreases in both insulin secretion and Si across populations (P < 0.001), although Si did not differ significantly between PDM and T2DM populations. Reproducibility was generally good for the MMTT, with intraclass correlation coefficients (ICCs) ranging from ∼0.3 to ∼0.8 depending on population and variable. Reproducibility for the AST was very good, with ICC values >0.8 across all variables and populations. CONCLUSIONS: Standardized MMTT and AST provide reproducible and complementary measures of BCF with characteristics favorable for longitudinal interventional trials use.

Hepatic and Extrahepatic Insulin Clearance Are Differentially Regulated: Results From a Novel Model-Based Analysis of Intravenous Glucose Tolerance Data.

Insulin clearance is a highly variable and important factor that affects circulating insulin concentrations. We developed a novel model-based method to estimate both hepatic and extrahepatic insulin clearance using plasma insulin and C-peptide profiles obtained from the insulin-modified frequently sampled intravenous glucose tolerance test. Data from 100 African immigrants without diabetes (mean age 38 years, body weight 81.7 kg, fasting plasma glucose concentration 83 mg/dL, and fasting insulin concentration 37 pmol/L) were used. Endogenous insulin secretion (calculated by C-peptide deconvolution) and insulin infusion rates were used as inputs to a new two-compartment model of insulin kinetics and hepatic and extrahepatic clearance parameters were estimated. Good agreement between modeled and measured plasma insulin profiles was observed (mean normalized root mean square error 6.8%), and considerable intersubject variability in parameters of insulin clearance among individuals was identified (the mean [interquartile range] for hepatic extraction was 25.8% [32.7%], and for extrahepatic insulin clearance was 20.7 mL/kg/min [11.7 mL/kg/min]). Parameters of insulin clearance were correlated with measures of insulin sensitivity and acute insulin response to glucose. The method described appears promising for future research aimed at characterizing variability in insulin clearance and the mechanisms involved in the regulation of insulin clearance.