Gene expression profile of subcutaneous adipose tissue in BMI-discordant monozygotic twin pairs unravels molecular and clinical changes associated with sub-types of obesity.

BACKGROUND: Subcutaneous adipose tissue (SAT) undergoes major changes in obesity, but little is known about the whole-genome scale patterns of these changes or about their variation between different obesity sub-groups. We sought to compare how transcriptomics profiles in SAT differ between monozygotic (MZ) co-twins who are discordant for body mass index (BMI), whether the profiles vary between twin pairs and whether the variation can be linked to clinical characteristics. METHODS: We analysed the transcriptomics (Affymetrix U133 Plus 2.0) patterns of SAT in young MZ twin pairs (n=26, intra-pair difference in BMI >3 kg m-2, aged 23-36), from 10 birth cohorts of adult Finnish twins. The clinical data included measurements of body composition, insulin resistance, lipids and adipokines. RESULTS: We found 2108 genes differentially expressed (false discovery rate (FDR)<0.05) in SAT of the BMI-discordant pairs. Pathway analyses of these genes revealed a significant downregulation of mitochondrial oxidative pathways (P<0.05) and upregulation of inflammation pathways (P<0.05). Hierarchical clustering of heavy/lean twin ratios, representing effects of acquired obesity in the transcriptomics data, revealed three sub-groups with different molecular profiles (FDR<0.05). Analyses comparing these sub-groups showed that, in the heavy co-twins, downregulation of the mitochondrial pathways, especially that of branched chain amino acid degradation was more evident in two clusters while and upregulation of the inflammatory response was most evident in the last, presumably the unhealthiest cluster. High-fasting insulin levels and large adipocyte diameter were the predominant clinical characteristic of the heavy co-twins in this cluster (Bonferroni-adjusted P<0.05). CONCLUSIONS: This is the first study in BMI-discordant MZ twin pairs reporting sub-types of obesity based on both SAT gene expression profiles and clinical traits. We conclude that a decrease in mitochondrial BCAA degradation and an increase in inflammation in SAT co-occur and associate with hyperinsulinemia and large adipocyte size in unhealthy obesity.

Efficacy and safety of linagliptin as add-on therapy to basal insulin and metformin in people with Type 2 diabetes.

AIM: To evaluate the efficacy and safety of linagliptin in people with Type 2 diabetes inadequately controlled on basal insulin and metformin. METHODS: This was a post hoc subanalysis of participants who received basal insulin and metformin in a global phase III study that randomized participants (1:1) to receive linagliptin 5 mg once daily or placebo for ≥52 weeks as add-on therapy to basal insulin alone or in combination with metformin and/or pioglitazone. During the first 24 weeks, the background dose of basal insulin remained stable; thereafter, adjustments based on glucose concentrations were recommended. The primary endpoint of the subanalysis was the change from baseline in HbA1c after 24 weeks. The safety analysis incorporated data up to a maximum of 110 weeks. RESULTS: A total of 950 participants receiving background insulin and metformin were included in this subanalysis (linagliptin and placebo, both n = 475). At week 24, the placebo-corrected adjusted mean (±se) change from baseline in HbA1c with linagliptin was -7 (±1) mmol/mol [-0.7 (±0.1) %; 95% CI -0.8, -0.6; P < 0.0001]. The overall frequency of drug-related adverse events (linagliptin, 18.9%; placebo, 21.9%) and investigator-reported hypoglycaemia (linagliptin, 30.7%; placebo, 31.6%) were similar in both groups at the end of treatment. The frequency of severe hypoglycaemia was low (linagliptin, 1.7%; placebo, 0.8%). No meaningful changes in mean (±sd) body weight were noted in either group [week 52: linagliptin, -0.5 (±3.2) kg; placebo, 0.0 (±3.1) kg]. CONCLUSIONS: Linagliptin added to basal insulin and metformin improved glycaemic control, without increasing the risk of hypoglycaemia or body weight gain.

Patient-level meta-analysis of the EDITION 1, 2 and 3 studies: glycaemic control and hypoglycaemia with new insulin glargine 300 U/ml versus glargine 100 U/ml in people with type 2 diabetes.

AIMS: To conduct a patient-level meta-analysis of the EDITION 1, 2 and 3 studies, which compared the efficacy and safety of new insulin glargine 300 U/ml (Gla-300) with insulin glargine 100 U/ml (Gla-100) in people with type 2 diabetes (T2DM) on basal and mealtime insulin, basal insulin and oral antihyperglycaemic drugs, or no prior insulin, respectively. METHODS: The EDITION studies were multicentre, randomized, open-label, parallel-group, phase IIIa studies, with similar designs and endpoints. A patient-level meta-analysis of the studies enabled these endpoints to be examined over 6 months in a large population with T2DM (Gla-300, n = 1247; Gla-100, n = 1249). RESULTS: No significant study-by-treatment interactions across studies were found, enabling them to be pooled. The mean change in glycated haemoglobin was comparable for Gla-300 and Gla-100 [each -1.02 (standard error 0.03)%; least squares (LS) mean difference 0.00 (95% confidence interval (CI) -0.08 to 0.07)%]. Annualized rates of confirmed (≤3.9 mmol/l) or severe hypoglycaemia were lower with Gla-300 than with Gla-100 during the night (31% difference in rate ratio over 6 months) and at any time (24 h, 14% difference). Consistent reductions were observed in percentage of participants with ≥1 hypoglycaemic event. Severe hypoglycaemia at any time (24 h) was rare (Gla-300: 2.3%; Gla-100: 2.6%). Weight gain was low (<1 kg) in both groups, with less gain with Gla-300 [LS mean difference -0.28 kg (95% CI -0.55 to -0.01); p = 0.039]. Both treatments were well tolerated, with similar rates of adverse events. CONCLUSION: Gla-300 provides comparable glycaemic control to Gla-100 in a large population with a broad clinical spectrum of T2DM, with consistently less hypoglycaemia at any time of day and less nocturnal hypoglycaemia.

Comparison of insulin glargine and liraglutide added to oral agents in patients with poorly controlled type 2 diabetes.

AIM: To compare safety and efficacy of insulin glargine and liraglutide in patients with type 2 diabetes (T2DM). METHODS: This randomized, multinational, open-label trial included subjects treated for T2DM with metformin ± sulphonylurea, who had glycated haemoglobin (HbA1c) levels of 7.5-12%. Subjects were assigned to 24 weeks of insulin glargine, titrated to target fasting plasma glucose of 4.0-5.5 mmol/L or liraglutide, escalated to the highest approved clinical dose of 1.8 mg daily. The trial was powered to detect superiority of glargine over liraglutide in percentage of people reaching HbA1c <7%. RESULTS: The mean [standard deviation (s.d.)] age of the participants was 57 (9) years, the duration of diabetes was 9 (6) years, body mass index was 31.9 (4.2) kg/m(2) and HbA1c level was 9.0 (1.1)%. Equal numbers (n = 489) were allocated to glargine and liraglutide. Similar numbers of subjects in both groups attained an HbA1c level of <7% (48.4 vs. 45.9%); therefore, superiority of glargine over liraglutide was not observed (p = 0.44). Subjects treated with glargine had greater reductions of HbA1c [-1.94% (0.05) and -1.79% (0.05); p = 0.019] and fasting plasma glucose [6.2 (1.6) and 7.9 (2.2) mmol/L; p < 0.001] than those receiving liraglutide. The liraglutide group reported a greater number of gastrointestinal treatment-emergent adverse events (p < 0.001). The mean (s.d.) weight change was +2.0 (4.0) kg for glargine and -3.0 (3.6) kg for liraglutide (p < 0.001). Symptomatic hypoglycaemia was more common with glargine (p < 0.001). A greater number of subjects in the liraglutide arm withdrew as a result of adverse events (p < 0.001). CONCLUSION: Adding either insulin glargine or liraglutide to subjects with poorly controlled T2DM reduces HbA1c substantially, with nearly half of subjects reaching target levels of 7%.

Glycaemic control and hypoglycaemia with new insulin glargine 300 U/ml versus insulin glargine 100 U/ml in people with type 2 diabetes using basal insulin and oral antihyperglycaemic drugs: the EDITION 2 randomized 12-month trial including 6-month extension.

AIMS: To compare the efficacy and safety of new insulin glargine 300 U/ml (Gla-300) with insulin glargine 100 U/ml (Gla-100) over 12 months of treatment in people with type 2 diabetes using basal insulin and oral antihyperglycaemic drugs (OADs). METHODS: EDITION 2 (NCT01499095) was a randomized, 6-month, multicentre, open-label, two-arm, phase IIIa study investigating once-daily Gla-300 versus Gla-100, plus OADs (excluding sulphonylureas), with a 6-month safety extension. RESULTS: Similar numbers of participants in each group completed 12 months of treatment [Gla-300, 315 participants (78%); Gla-100, 314 participants (77%)]. The reduction in glycated haemoglobin was maintained for 12 months with both treatments: least squares (LS) mean (standard error) change from baseline -0.55 (0.06)% for Gla-300 and -0.50 (0.06)% for Gla-100; LS mean difference -0.06 [95% confidence interval (CI) -0.22 to 0.10)%]. A significant relative reduction of 37% in the annualized rate of nocturnal confirmed [≤3.9 mmol/l (≤70 mg/dl)] or severe hypoglycaemia was observed with Gla-300 compared with Gla-100: rate ratio 0.63 [(95% CI 0.42-0.96); p = 0.031], and fewer participants experienced ≥1 event [relative risk 0.84 (95% CI 0.71-0.99)]. Severe hypoglycaemia was infrequent. Weight gain was significantly lower with Gla-300 than Gla-100 [LS mean difference -0.7 (95% CI -1.3 to -0.2) kg; p = 0.009]. Both treatments were well tolerated with a similar pattern of adverse events (incidence of 69 and 60% in the Gla-300 and Gla-100 groups). CONCLUSIONS: In people with type 2 diabetes treated with Gla-300 or Gla-100, and non-sulphonylurea OADs, glycaemic control was sustained over 12 months, with less nocturnal hypoglycaemia in the Gla-300 group.

One-year sustained glycaemic control and less hypoglycaemia with new insulin glargine 300 U/ml compared with 100 U/ml in people with type 2 diabetes using basal plus meal-time insulin: the EDITION 1 12-month randomized trial, including 6-month extension.

AIMS: To evaluate the maintenance of efficacy and safety of insulin glargine 300 U/ml (Gla-300) versus glargine 100 U/ml (Gla-100) in people with type 2 diabetes mellitus (T2DM) using basal plus meal-time insulin for 12 months in the EDITION 1 trial. METHODS: EDITION 1 was a multicentre, randomized, open-label, two-arm, phase IIIa study. Participants completing the initial 6-month treatment period continued to receive Gla-300 or Gla-100, as previously randomized, once daily for a further 6-month open-label extension phase. Changes in glycated haemoglobin (HbA1c) and fasting plasma glucose concentrations, insulin dose, hypoglycaemic events and body weight were assessed. RESULTS: Of 807 participants enrolled in the initial phase, 89% (359/404) assigned to Gla-300 and 88% (355/403) assigned to Gla-100 completed 12 months. Glycaemic control was sustained in both groups (mean HbA1c: Gla-300, 7.24%; Gla-100, 7.42%), with more sustained HbA1c reduction for Gla-300 at 12 months: least squares mean difference Gla-300 vs Gla-100: HbA1c -0.17 [95% confidence interval (CI) -0.30 to -0.05]%. The mean daily basal insulin dose at 12 months was 1.03 U/kg for Gla-300 and 0.90 U/kg for Gla-100. Lower percentages of participants had ≥1 confirmed [≤3.9 mmol/l (≤70 mg/dl)] or severe hypoglycaemic event with Gla-300 than Gla-100 at any time of day [24 h; 86 vs 92%; relative risk 0.94 (95% CI 0.89-0.99)] and during the night [54 vs 65%; relative risk 0.84 (95% CI 0.75-0.94)], while the annualized rates of such hypoglycaemic events were similar. No between-treatment differences in adverse events were apparent. CONCLUSION: During 12 months of treatment of T2DM requiring basal and meal-time insulin, glycaemic control was better sustained and fewer individuals reported hypoglycaemia with Gla-300 than with Gla-100. The mean basal insulin dose was higher with Gla-300 compared with Gla-100, but total numbers of hypoglycaemic events and overall tolerability did not differ between treatments.

Adipose tissue is inflamed in NAFLD due to obesity but not in NAFLD due to genetic variation in PNPLA3.

AIMS/HYPOTHESIS: The rs738409 C>G single-nucleotide polymorphism in PNPLA3 leads to a missense mutation (I148M) which increases liver fat but does not cause insulin resistance. We hypothesised that patients with non-alcoholic fatty liver disease (NAFLD) due to the PNPLA3 variant ('PNPLA3 NAFLD' = PNPLA3-148MM) do not have adipose tissue (AT) inflammation in contrast with those with NAFLD due to obesity ('obese NAFLD'). METHODS: Biopsy specimens of AT were taken, and PNPLA3 genotype and liver fat ((1)H-magnetic resonance spectroscopy) were determined in 82 volunteers, who were divided into groups based on either median BMI (obese 36.2 ± 0.7 kg/m(2); non-obese 26.0 ± 0.4 kg/m(2)) or PNPLA3 genotype. All groups were similar with respect to age and sex. The PNPLA3 subgroups were equally obese (PNPLA3-148MM, 31.1 ± 1.3 kg/m(2); PNPLA3-148II, 31.2 ± 0.8 kg/m(2)), while the obese and non-obese subgroups had similar PNPLA3 genotype distribution. Gene expression of proinflammatory (MCP-1, CD68) and anti-inflammatory (Twist1, ADIPOQ) markers was measured using quantitative real-time RT-PCR. RESULTS: Liver fat was similarly increased in obese NAFLD (9.5 ± 1.3% vs 5.1 ± 0.9%, obese vs non-obese, p = 0.007) and PNPLA3 NAFLD (11.4 ± 1.7% vs 5.3 ± 0.8%, PNPLA3-148MM vs PNPLA3-148II, p < 0.001). Fasting serum insulin was higher in the obese than the non-obese group (76 ± 6 vs 47 ± 6 pmol/l, p < 0.001), but similar in PNPLA3-148MM and PNPLA3-148II (60 ± 8 vs 62 ± 5 pmol/l, NS). In obese vs non-obese, MCP-1 and CD68 mRNAs were upregulated, whereas those of Twist1 and ADIPOQ were significantly downregulated. AT gene expression of MCP-1, CD68, Twist1 and ADIPOQ was similar in PNPLA3-148MM and PNPLA3-148II groups. CONCLUSIONS/INTERPRETATION: PNPLA3 NAFLD is characterised by an increase in liver fat but no insulin resistance or AT inflammation, while obese NAFLD has all three of these features.

CB(1) blockade-induced weight loss over 48 weeks decreases liver fat in proportion to weight loss in humans.

OBJECTIVE: Studies in mice have suggested that endocannabinoid blockade using the cannabinoid receptor type 1 (CB1) blocker rimonabant prevents obesity-induced hepatic steatosis. DESIGN AND SUBJECTS: To determine effects of rimonabant on liver fat in humans, we measured liver fat content by proton magnetic resonance spectroscopy in 37 subjects who used either a CB1 blocker rimonabant or placebo in a double-blind, randomized manner. This was retrospectively compared with a historical hypocaloric diet weight loss group (n=23). RESULTS: Weight loss averaged 8.5±1.4 kg in the rimonabant, 1.7±1.0 kg in the placebo and 7.5±0.2 kg in the hypocaloric diet group (P<0.001, rimonabant vs placebo; NS, rimonabant vs hypocaloric diet). Liver fat decreased more in the rimonabant (5.9% (2.5-14.6%) vs 1.8% (0.9-3.5%), before vs after) than in the placebo group (6.8% (2.2-15.7%) vs 4.9% (1.6-7.8%), before vs after, P<0.05). The percentage change in body weight correlated closely with the percentage loss of liver fat (r=0.70, P>0.0001). The decreases in liver fat were comparable between the rimonabant and the young historical hypocaloric diet groups. CONCLUSIONS: We conclude that, unlike in mice, in humans rimonabant decreases liver fat in proportion to weight loss.

Addition of insulin glargine or NPH insulin to metformin monotherapy in poorly controlled type 2 diabetic patients decreases IGF-I bioactivity similarly.

AIMS/HYPOTHESIS: The aim of this study was to compare IGF-I bioactivity 36 weeks after the addition of insulin glargine (A21Gly,B31Arg,B32Arg human insulin) or NPH insulin to metformin therapy in type 2 diabetic patients who had poor glucose control under metformin monotherapy. METHODS: In the Lantus plus Metformin (LANMET) study, 110 poorly controlled insulin-naive type 2 diabetic patients were randomised to receive metformin with either insulin glargine (G+MET) or NPH insulin (NPH+MET). In the present study, IGF-I bioactivity was measured, retrospectively, in 104 out of the 110 initially included LANMET participants before and after 36 weeks of insulin therapy. IGF-I bioactivity was measured using an IGF-I kinase receptor activation assay. RESULTS: After 36 weeks of insulin therapy, insulin doses were comparable between the G+MET (68 ± 5.7 U/day) and NPH+MET (71 ± 6.2 U/day) groups (p = 0.68). Before insulin therapy, circulating IGF-I bioactivity was similar between the G+MET (134 ± 9 pmol/l) and NPH+MET (135 ± 10 pmol/l) groups (p = 0.83). After 36 weeks, IGF-I bioactivity had decreased significantly (p = 0.001) and did not differ between the G+MET (116 ± 9 pmol/l) and NPH+MET (117 ± 10 pmol/l) groups (p = 0.91). At baseline and after insulin therapy, total IGF-I concentrations were comparable in both groups (baseline: G+MET 13.3 ± 1.0 vs NPH+MET 13.3 ± 1.0 nmol/l, p = 0.97; and 36 weeks: 13.4 ± 1.0 vs 13.1 ± 0.9 nmol/l, p = 0.71). Total IGF-I concentration did not change during insulin therapy (13.3 ± 0.7 vs 13.3 ± 0.7 nmol/l, baseline vs 36 weeks, p = 0.86). CONCLUSIONS/INTERPRETATION: Addition of insulin glargine or NPH insulin to metformin monotherapy in poorly controlled type 2 diabetic patients decreases serum IGF-I bioactivity in a similar manner.

Exenatide treatment did not affect bone mineral density despite body weight reduction in patients with type 2 diabetes.

Preclinical studies suggest that incretin-based therapies may be beneficial for the bone; however, clinical data are largely lacking. We assessed whether the differential effects of these therapies on body weight differed with respect to their effect on bone mineral density (BMD) and markers of calcium homeostasis in patients with type 2 diabetes (T2D). Sixty-nine metformin-treated patients with T2D were randomized to exenatide twice daily (n = 36) or insulin glargine once daily (n = 33). Total body BMD, measured by dual-energy X-ray absorptiometry, and serum markers of calcium homeostasis were assessed before and after 44-week treatment. Exenatide or insulin glargine treatment decreased body weight by 6%. Endpoint BMD was similar in both groups after 44-week therapy (LSmean ± s.e.m. between-group difference -0.002 ± 0.007 g/cm(2) ; p = 0.782). Fasting serum alkaline phosphatase, calcium and phosphate remained unaffected. Forty-four-week treatment with exenatide or insulin glargine had no adverse effects on bone density in patients with T2D, despite differential effects on body weight.

Inaccuracies in food and physical activity diaries of obese subjects: complementary evidence from doubly labeled water and co-twin assessments.

OBJECTIVE: To study whether eating or physical-activity (PA) habits differ between obese and non-obese monozygotic (MZ) co-twins independent of genetic effects. METHODS: Rare MZ pairs discordant for obesity (n=14, body mass index difference 5.2+/-1.8 kg m(-2)) and weight-concordant control pairs (n=10, 1.0+/-0.7 kg m(-2)), identified through a population-based registry of 24-28-year-old twins (n=658 MZ pairs), completed 3-day food and PA diaries and eating behavior questionnaires. Each twin was asked to compare his/her own eating and PA patterns with the co-twin's behavior by structured questionnaires. Accuracy of energy intake was validated by doubly labeled water. RESULTS: Non-obese co-twins consistently reported that their obese twin siblings ate more food overall, consumed less healthy foods and exercised less than the non-obese co-twins do. However, no differences in energy intake (9.6+/-1.0 MJ per day vs 9.8+/-1.1 MJ per day, respectively) in the food diaries or in the mean PA level (1.74+/-0.02 vs 1.79+/-0.04, respectively) in the PA diaries were found between obese and non-obese co-twins. A considerable underreporting of energy intake (3.2+/-1.1 MJ per day, P=0.036) and overreporting of PA (1.8+/-0.8 MJ per day, P=0.049) was observed in the obese, but not in the non-obese co-twins. CONCLUSIONS: On the basis of rare MZ twin pairs discordant for obesity, the co-twin assessments confirmed substantial differences in eating and PA behavior between obese and non-obese persons. These may be overlooked in population studies using food and PA diaries because of considerable misreporting by the obese.

Efficacy and safety of sitagliptin when added to insulin therapy in patients with type 2 diabetes.

OBJECTIVE: To evaluate the efficacy and tolerability of sitagliptin when added to insulin therapy alone or in combination with metformin in patients with type 2 diabetes. METHODS: After a 2 week placebo run-in period, eligible patients inadequately controlled on long-acting, intermediate-acting or premixed insulin (HbA1c > or = 7.5% and < or = 11%), were randomised 1:1 to the addition of once-daily sitagliptin 100 mg or matching placebo over a 24-week study period. The study capped the proportion of randomised patients on insulin plus metformin at 75%. Further, the study capped the proportion of randomised patients on premixed insulin at 25%. The metformin dose and the insulin dose were to remain stable throughout the study. The primary endpoint was HbA1c change from baseline at week 24. RESULTS: Mean baseline characteristics were similar between the sitagliptin (n = 322) and placebo (n = 319) groups, including HbA1c (8.7 vs. 8.6%), diabetes duration (13 vs. 12 years), body mass index (31.4 vs. 31.4 kg/m(2)), and total daily insulin dose (51 vs. 52 IU), respectively. At 24 weeks, the addition of sitagliptin significantly (p < 0.001) reduced HbA1c by 0.6% compared with placebo (0.0%). A greater proportion of patients achieved an HbA1c level < 7% while randomised to sitagliptin as compared with placebo (13 vs. 5% respectively; p < 0.001). Similar HbA1c reductions were observed in the patient strata defined by insulin type (long-acting and intermediate-acting insulins or premixed insulins) and by baseline metformin treatment. The addition of sitagliptin significantly (p < 0.001) reduced fasting plasma glucose by 15.0 mg/dl (0.8 mmol/l) and 2-h postmeal glucose by 36.1 mg/dl (2.0 mmol/l) relative to placebo. A higher incidence of adverse experiences was reported with sitagliptin (52%) compared with placebo (43%), due mainly to the increased incidence of hypoglycaemia (sitagliptin, 16% vs. placebo, 8%). The number of hypoglycaemic events meeting the protocol-specified criteria for severity was low with sitagliptin (n = 2) and placebo (n = 1). No significant change from baseline in body weight was observed in either group. CONCLUSION: In this 24-week study, the addition of sitagliptin to ongoing, stable-dose insulin therapy with or without concomitant metformin improved glycaemic control and was generally well tolerated in patients with type 2 diabetes.

Serum saturated fatty acids containing triacylglycerols are better markers of insulin resistance than total serum triacylglycerol concentrations.

AIMS/HYPOTHESIS: The weak relationship between insulin resistance and total serum triacylglycerols (TGs) could be in part due to heterogeneity of TG molecules and their distribution within different lipoproteins. We determined concentrations of individual TGs and the fatty acid composition of serum and major lipoprotein particles and analysed how changes in different TGs and fatty acid composition are related to features of insulin resistance and abdominal obesity. METHODS: We performed lipidomic analyses of all major lipoprotein fractions using two analytical platforms in 16 individuals, who exhibited a broad range of insulin sensitivity. RESULTS: We identified 45 different TGs in serum. Serum TGs containing saturated and monounsaturated fatty acids were positively, while TGs containing essential linoleic acid (18:2 n-6) were negatively correlated with HOMA-IR. Specific serum TGs that correlated positively with HOMA-IR were also significantly positively related to HOMA-IR when measured in very-low-density lipoproteins (VLDLs), intermediate-density lipoproteins (IDLs) and LDL, but not in HDL subfraction 2 (HDL(2)) or 3 (HDL(3)). Analyses of proportions of esterified fatty acids within lipoproteins revealed that palmitic acid (16:0) was positively related to HOMA-IR when measured in VLDL, IDL and LDL, but not in HDL(2) or HDL(3). Monounsaturated palmitoleic (16:1 n-7) and oleic (18:1 n-9) acids were positively related to HOMA-IR when measured in HDL(2) and HDL(3), but not in VLDL, IDL or LDL. Linoleic acid was negatively related to HOMA-IR in all lipoproteins. CONCLUSIONS/INTERPRETATION: Serum concentrations of specific TGs, such as TG(16:0/16:0/18:1) or TG(16:0/18:1/18:0), may be more precise markers of insulin resistance than total serum TG concentrations.

A common variant in PNPLA3, which encodes adiponutrin, is associated with liver fat content in humans.

AIMS/HYPOTHESIS: It has recently been suggested that the rs738409 G allele in PNPLA3, which encodes adiponutrin, is strongly associated with increased liver fat content in three different ethnic groups. The aims of the present study were as follows: (1) to try to replicate these findings in European individuals with quantitative measures of hepatic fat content; (2) to study whether the polymorphism influences hepatic and adipose tissue insulin sensitivity; and (3) to investigate whether PNPLA3 expression is altered in the human fatty liver. METHODS: We genotyped 291 Finnish individuals in whom liver fat had been measured using proton magnetic resonance spectroscopy. Hepatic PNPLA3 expression was measured in 32 participants. Hepatic and adipose tissue insulin sensitivities were measured using a euglycaemic-hyperinsulinaemic (insulin infusion 0.3 mU kg(-1) min(-1)) clamp technique combined with infusion of [3-(3)H]glucose in 109 participants. RESULTS: The rs738409 G allele in PNPLA3 was associated with increased quantitative measures of liver fat content (p = 0.011) and serum aspartate aminotransferase concentrations (p = 0.002) independently of age, sex and BMI. Fasting serum insulin and hepatic and adipose tissue insulin sensitivity were related to liver fat content independently of genotype status. PNPLA3 mRNA expression in the liver was positively related to obesity (r = 0.62, p < 0.0001) and to liver fat content (r = 0.58, p = 0.025) in participants who were not morbidly obese (BMI < 40 kg/m(2)). CONCLUSIONS/INTERPRETATION: A common variant in PNPLA3 increases the risk of hepatic steatosis in humans.

Nateglinide combination therapy with basal insulin and metformin in patients with Type 2 diabetes.

AIMS: To compare the effect of adding nateglinide or placebo on postprandial glucose excursions (PPGEs), glycated haemoglobin (HbA(1c)), diurnal glucose profiles and hypoglycaemia in patients with Type 2 diabetes treated with the combination of basal insulin and metformin. RESEARCH DESIGN AND METHODS: This was an investigator-initiated, double-blind, randomized, parallel-group, study in five centres. Patients with Type 2 diabetes (n = 88, age 56.0 +/- 0.9 years, duration of diabetes 9.4 +/- 0.5 years, HbA(1c) 7.8 +/- 0.1%, body mass index 32.4 +/- 0.5 kg/m(2)) treated with basal insulin and metformin entered a 24-week period, during which basal insulin was titrated to optimize glucose control. Thereafter, the patients were randomized to receive either nateglinide (120 mg three times daily) or placebo before their main meals for 24 weeks. RESULTS: During the optimization period, HbA(1c) decreased by -0.3 +/- 0.1 and -0.4 +/- 0.2% (NS) and insulin doses increased by 10.0 IU (2.0-32.0) [0.09 IU/kg (0.02-0.34)] and 10.0 IU (0.0-19.0) [0.11 IU/kg (0.0-0.25)] (NS) in the nateglinide and placebo groups. Mean postprandial glucose during weeks 20-24 averaged 9.0 +/- 0.3 and 10.0 +/- 0.3 mmol/l in the nateglinide and placebo groups (P = 0.025) and mean PPGE averaged 2.4 +/- 0.2 and 3.1 +/- 0.2 mmol/l, respectively (P = 0.019). At 24 weeks as compared with 0 weeks, mean HbA(1c) had decreased by 0.41 +/- 0.12% in the nateglinide group and by 0.04 +/- 0.12% in the placebo group (P = 0.023). The frequency of confirmed, symptomatic hypoglycaemia was 7.7 episodes/patient-year vs. 4.7 episodes/patient-year in the nateglinide and placebo groups (P = 0.031). CONCLUSIONS: Addition of a short-acting insulin secretagogue at main meals improves postprandial hyperglycaemia during combination therapy with basal insulin and metformin, but increases the frequency of hypolycaemia.

Exenatide twice-daily does not affect renal function or albuminuria compared to titrated insulin glargine in patients with type 2 diabetes mellitus: A post-hoc analysis of a 52-week randomised trial.

AIMS: To compare the effects of long-term treatment with the GLP-1RA exenatide twice-daily versus titrated insulin glargine (iGlar) on renal function and albuminuria in type 2 diabetes (T2DM) patients. METHODS: We post-hoc evaluated renal outcome-data of 54 overweight T2DM patients (mean  ±â€¯SD age 60 ±â€¯8 years, HbA1c 7.5 ±â€¯0.9%, eGFR 86 ±â€¯16 mL/min/1.73 m2, median [IQR] urinary albumin-to-creatinine-ratio (UACR) 0.75 [0.44-1.29] mg/mmol) randomised to exenatide 10 µg twice-daily or titrated iGlar on-top-of metformin for 52-weeks. Renal efficacy endpoints were change in creatinine clearance (CrCl) and albuminuria (urinary albumin-excretion [UAE] and UACR) based on 24-h urines, collected at baseline and Week-52. eGFR and exploratory endpoints were collected throughout the intervention-period, and after a 4-week wash-out. RESULTS: HbA1c-reductions were similar with exenatide (mean ±â€¯SEM -0.80 ±â€¯0.10%) and iGlar (-0.79 ±â€¯0.14%; treatment-difference 0.02%; 95% CI -0.31 to 0.42%). Change from baseline to Week-52 in CrCl, UAE or UACR did not statistically differ; only iGlar reduced albuminuria (P < 0.05; within-group). eGFR decreased from baseline to Week-4 with exenatide (-3.9 ±â€¯2.1 mL/min/1.73 m2; P = 0.069) and iGlar (-2.7 ±â€¯1.2 mL/min/1.73 m2; P = 0.034), without treatment-differences in ensuing trajectory. Exenatide versus iGlar reduced bodyweight (-5.4 kg; 2.9-7.9; P < 0.001), but did not affect blood pressure, lipids or plasma uric acid. CONCLUSIONS: Among T2DM patients without overt nephropathy, one-year treatment with exenatide twice-daily does not affect renal function-decline or onset/progression of albuminuria compared to titrated iGlar. TRIAL REGISTRATION: ClinicalTrials.gov ID: NCT00097500.

Kinetics of glucose disposal in whole body and across the forearm in man.

We reevaluated the concept that the in vivo glucose disposal rate in man is determined by the activity of the glucose transport system. Rates of glucose disposal were determined in whole body and across forearm at four insulin levels (approximately 9, approximately 50, approximately 160, and approximately 1700 microU/ml) and at each insulin level at four glucose levels (approximately 90, approximately 160, approximately 250, and approximately 400 mg/dl). At the lowest insulin level, the Michaelis constants (Ks:s) for glucose disposal in whole body (8.7 +/- 1.1 mM) and across forearm (7.4 +/- 1.4) mM) were compatible with a Ks determined in vitro for the transport system. At higher insulin levels, the apparent Ks increased significantly in whole body (16.2-37.7 mM) and across forearm (20.7-31.2 mM). We interpret the apparent increase of Ks by insulin to reflect a shift in the rate-limiting step from glucose transport to some step beyond transport.

Regulation of glycogen synthase and phosphorylase activities by glucose and insulin in human skeletal muscle.

We examined the insulin dose-response characteristics of human muscle glycogen synthase and phosphorylase activation. We also determined whether increasing the rate of glucose disposal by hyperglycemia at a fixed insulin concentration activates glycogen synthase. Physiological increments in plasma insulin but not glucose increased the fractional activity of glycogen synthase. The ED50: s for insulin stimulation of whole body and forearm glucose disposal were similar and unaffected by glycemia. Glycogen synthase activation was exponentially related to the insulin-mediated component of whole body and forearm glucose disposal at each glucose concentration. Neither insulin nor glucose changed glycogen phosphorylase activity. These results suggest that insulin but not the rate of glucose disposal per se regulates glycogen synthesis by a mechanism that involves dephosphorylation of glycogen synthase but not phosphorylase. This implies that the low glycogen synthase activities found in insulin-resistant states are a consequence of impaired insulin action rather than reduced glucose disposal.

Insulin resistance of glucose uptake in skeletal muscle cannot be ameliorated by enhancing endothelium-dependent blood flow in obesity.

We tested the hypothesis that endothelium-dependent vasodilatation is a determinant of insulin resistance of skeletal muscle glucose uptake in human obesity. Eight obese (age 26+/-1 yr, body mass index 37+/-1 kg/m2) and seven nonobese males (25+/-2 yr, 23+/-1 kg/m2) received an infusion of bradykinin into the femoral artery of one leg under intravenously maintained normoglycemic hyperinsulinemic conditions. Blood flow was measured simultaneously in the bradykinin and insulin- and the insulin-infused leg before and during hyperinsulinemia using [15O]-labeled water ([15O]H2O) and positron emission tomography (PET). Glucose uptake was quantitated immediately thereafter in both legs using [18F]- fluoro-deoxy-glucose ([18F]FDG) and PET. Whole body insulin-stimulated glucose uptake was lower in the obese (507+/-47 mumol/m2 . min) than the nonobese (1205+/-97 micromol/m2 . min, P < 0.001) subjects. Muscle glucose uptake in the insulin-infused leg was 66% lower in the obese (19+/-4 micromol/kg muscle . min) than in the nonobese (56+/-9 micromol/kg muscle . min, P < 0.005) subjects. Bradykinin increased blood flow during hyperinsulinemia in the obese subjects by 75% from 16+/-1 to 28+/-4 ml/kg muscle . min (P < 0.05), and in the normal subjects by 65% from 23+/-3 to 38+/-9 ml/kg muscle . min (P < 0.05). However, this flow increase required twice as much bradykinin in the obese (51+/-3 microg over 100 min) than in the normal (25+/-1 mug, P < 0.001) subjects. In the obese subjects, blood flow in the bradykinin and insulin-infused leg (28+/-4 ml/kg muscle . min) was comparable to that in the insulin-infused leg in the normal subjects during hyperinsulinemia (24+/-5 ml/kg muscle . min). Despite this, insulin-stimulated glucose uptake remained unchanged in the bradykinin and insulin-infused leg (18+/-4 mumol/kg . min) compared with the insulin-infused leg (19+/-4 micromol/kg muscle . min) in the obese subjects. Insulin-stimulated glucose uptake also was unaffected by bradykinin in the normal subjects (58+/-10 vs. 56+/-9 micromol/kg . min, bradykinin and insulin versus insulin leg). These data demonstrate that obesity is characterized by two distinct defects in skeletal muscle: insulin resistance of cellular glucose extraction and impaired endothelium-dependent vasodilatation. Since a 75% increase in blood flow does not alter glucose uptake, insulin resistance in obesity cannot be overcome by normalizing muscle blood flow.

Skeletal muscle capillary density and fiber type are possible determinants of in vivo insulin resistance in man.

We have compared the capillary density and muscle fiber type of musculus vastus lateralis with in vivo insulin action determined by the euglycemic clamp (M value) in 23 Caucasians and 41 Pima Indian nondiabetic men. M value was significantly correlated with capillary density (r = 0.63; P less than or equal to 0.0001), percent type I fibers (r = 0.29; P less than 0.02), and percent type 2B fibers (r = -0.38; P less than 0.003). Fasting plasma glucose and insulin concentrations were significantly negatively correlated with capillary density (r = -0.46, P less than or equal to 0.0001; r = -0.47, P less than or equal to 0.0001, respectively). Waist circumference/thigh circumference ratio was correlated with percent type 1 fibers (r = -0.39; P less than 0.002). These results suggest that diffusion distance from capillary to muscle cells or some associated biochemical change, and fiber type, could play a role in determining in vivo insulin action. The association of muscle fiber type with body fat distribution may indicate that central obesity is only one aspect of a more generalized metabolic syndrome. The data may provide at least a partial explanation for the insulin resistance associated with obesity and for the altered kinetics of insulin action in the obese.