Higher serum urate levels are associated with an increased risk of diabetic kidney disease. Lowering of the serum urate level with allopurinol may slow the decrease in the glomerular filtration rate ...(GFR) in persons with type 1 diabetes and early-to-moderate diabetic kidney disease.
In a double-blind trial, we randomly assigned participants with type 1 diabetes, a serum urate level of at least 4.5 mg per deciliter, an estimated GFR of 40.0 to 99.9 ml per minute per 1.73 m
of body-surface area, and evidence of diabetic kidney disease to receive allopurinol or placebo. The primary outcome was the baseline-adjusted GFR, as measured with iohexol, after 3 years plus a 2-month washout period. Secondary outcomes included the decrease in the iohexol-based GFR per year and the urinary albumin excretion rate after washout. Safety was also assessed.
A total of 267 patients were assigned to receive allopurinol and 263 to receive placebo. The mean age was 51.1 years, the mean duration of diabetes 34.6 years, and the mean glycated hemoglobin level 8.2%. The mean baseline iohexol-based GFR was 68.7 ml per minute per 1.73 m
in the allopurinol group and 67.3 ml per minute per 1.73 m
in the placebo group. During the intervention period, the mean serum urate level decreased from 6.1 to 3.9 mg per deciliter with allopurinol and remained at 6.1 mg per deciliter with placebo. After washout, the between-group difference in the mean iohexol-based GFR was 0.001 ml per minute per 1.73 m
(95% confidence interval CI, -1.9 to 1.9; P = 0.99). The mean decrease in the iohexol-based GFR was -3.0 ml per minute per 1.73 m
per year with allopurinol and -2.5 ml per minute per 1.73 m
per year with placebo (between-group difference, -0.6 ml per minute per 1.73 m
per year; 95% CI, -1.5 to 0.4). The mean urinary albumin excretion rate after washout was 40% (95% CI, 0 to 80) higher with allopurinol than with placebo. The frequency of serious adverse events was similar in the two groups.
We found no evidence of clinically meaningful benefits of serum urate reduction with allopurinol on kidney outcomes among patients with type 1 diabetes and early-to-moderate diabetic kidney disease. (Funded by the National Institute of Diabetes and Digestive and Kidney Diseases and others; PERL ClinicalTrials.gov number, NCT02017171.).
Context and Objective: Hyperinsulinemic hypoglycemia is newly recognized as a rare but important complication after Roux-en-Y gastric bypass (GB). The etiology of the syndrome and metabolic ...characteristics remain incompletely understood. Recent studies suggest that levels of incretin hormones are increased after GB and may promote excessive β-cell function and/or growth.
Patients and Methods: We performed a cross-sectional analysis of metabolic variables, in both the fasting state and after a liquid mixed-meal challenge, in four subject groups: 1) with clinically significant hypoglycemia neuroglycopenia (NG) after GB surgery, 2) with no symptoms of hypoglycemia at similar duration after GB surgery, 3) without GB similar to preoperative body mass index of the surgical cohorts, and 4) without GB similar to current body mass index of the surgical cohorts.
Results: Insulin and C-peptide after the liquid mixed meal were both higher relative to the glucose level achieved in persons after GB with NG compared with asymptomatic individuals. Glucagon, glucagon-like peptide 1, and glucose-dependent insulinotropic peptide levels were higher in both post-GB surgical groups compared with both overweight and morbidly obese persons, and glucagon-like peptide 1 was markedly higher in the group with NG. Insulin resistance, assessed by homeostasis model assessment of insulin resistance, the composite insulin sensitivity index, or adiponectin, was similar in both post-GB groups. Dumping score was also higher in both GB groups but did not discriminate between asymptomatic and symptomatic patients. Notably, the frequency of asymptomatic hypoglycemia after a liquid mixed meal was high in post-GB patients.
Conclusion: A robust insulin secretory response was associated with postprandial hypoglycemia in patients after GB presenting with NG. Increased incretin levels may contribute to the increased insulin secretory response.
Postprandial hypoglycaemia following gastric bypass for obesity is considered a late manifestation of the dumping syndrome and can usually be managed with dietary modification. We investigated three ...patients with severe postprandial hypoglycaemia and hyperinsulinaemia unresponsive to diet, octreotide and diazoxide with the aim of elucidating the pathological mechanisms involved.
Glucose, insulin, and C-peptide were measured in the fasting and postprandial state, and insulin secretion was assessed following selective intra-arterial calcium injection. Pancreas histopathology was assessed in all three patients.
All three patients had evidence of severe postprandial hyperinsulinaemia and hypoglycaemia. In one patient, reversal of gastric bypass was ineffective in reversing hypoglycaemia. All three patients ultimately required partial pancreatectomy for control of neuroglycopenia; pancreas pathology of all patients revealed diffuse islet hyperplasia and expansion of beta cell mass.
These findings suggest that gastric bypass-induced weight loss may unmask an underlying beta cell defect or contribute to pathological islet hyperplasia, perhaps via glucagon-like peptide 1-mediated pathways.
Aims/hypothesis
Chronic sub-acute inflammation contributes to the pathogenesis of type 2 diabetes mellitus and cardiovascular disease. High doses of salicylate reduce inflammation, glucose and ...triacylglycerols, and may improve insulin sensitivity, suggesting therapeutic potential in impaired fasting glucose and/or impaired glucose tolerance. This trial aimed to evaluate the effect of salsalate vs placebo on insulin resistance and glycaemia in impaired fasting glucose and/or impaired glucose tolerance.
Methods
We conducted a 12 week, two-centre, randomised, placebo-controlled study to evaluate the effect of salsalate (up to 4 g/day) vs placebo on systemic glucose disposal. Secondary objectives included treatment effects on glycaemia, inflammation and cardiovascular risk factors. Seventy-eight participants with impaired fasting glucose and/or impaired glucose tolerance from two VA healthcare systems were enrolled. Randomisation assignment was provided by the coordinating center directly to site pharmacists, and participants and research staff were blinded to treatment assignment.
Results
Seventy-one individuals were randomised to placebo (
n
= 36) or salsalate (
n
= 35). Glucose disposal did not change in either group (salsalate 1% 95% CI −39%, 56%; placebo 6% 95% CI −20%, 61%,
p
= 0.3 for placebo vs salsalate). Fasting glucose was reduced by 6% during the study by salsalate (
p
= 0.006) but did not change with placebo. Declines in glucose were accompanied by declines in fasting C-peptide with salsalate. Insulin clearance was reduced with salsalate. In the salsalate group, triacylglycerol levels were lower by 25% (
p
= 0.01) and adiponectin increased by 53% (
p
= 0.02) at the end of the study. Blood pressure, endothelial function and other inflammation markers did not differ between groups. Adipose tissue nuclear factor κB (NF-κB) activity declined in the salsalate group compared with placebo (−16% vs 42%,
p
= 0.005), but was not correlated with metabolic improvements. The frequency of tinnitus was low but tended to be higher with salsalate therapy (
n
= 4 vs
n
= 2).
Conclusions/interpretation
In summary, salsalate therapy was well tolerated, lowered fasting glucose, increased adiponectin and reduced adipose tissue NF-κB activity. These changes were not related to changes in peripheral insulin sensitivity, suggesting additional mechanisms for metabolic improvement.
Trial registration
ClinicalTrials.gov NCT00330733
Funding
Office of Research and Development, Medical Research Service, Department of Veterans Affairs and NIH K24 DK63214
Endothelial function is impaired in patients with diabetes mellitus. However, the factors contributing to this defect are currently unknown. Hyperglycemia attenuates endothelium-dependent relaxation ...in normal rabbit arteries in vitro and rat arterioles in vivo. Accordingly, this study examined the effect of acute hyperglycemia on endothelium-dependent vasodilation in nondiabetic humans in vivo.
Endothelium-dependent vasodilation was assessed through brachial artery infusion of methacholine chloride both before and during 6 hours of local hyperglycemia (300 mg/dL) achieved by intra-arterial infusion of 50% dextrose. Forearm blood flow was determined by plethysmography. In a group of 10 subjects, there was a trend toward attenuated methacholine-mediated vasodilation during hyperglycemia compared with euglycemia (P=.07 by ANOVA; maximal response, 13.3+/-2.8 versus 14.7+/-1.5 mL x min(-1) x 100 mL(-1), respectively). In these subjects, the systemic serum insulin levels increased significantly during the dextrose infusion (P<.001). To eliminate the confounding vasoactive effects of insulin, the protocol was repeated during systemic infusion of octreotide (30 ng x kg(-1) x min(-1)) to inhibit pancreatic secretion of insulin. In these subjects (n=10), hyperglycemia significantly attenuated the forearm blood flow response to methacholine (P<.01 by ANOVA; maximal response, 16.9+/-2.5 before versus 12.7+/-1.8 mL x min(-1) x 100 mL(-1) during hyperglycemia). Methacholine-mediated vasodilation was not attenuated by an equimolar infusion of mannitol (P>.40), nor did hyperglycemia reduce endothelium-independent vasodilation to verapamil (P>.50).
Acute hyperglycemia impairs endothelium-dependent vasodilation in healthy humans in vivo. This finding suggests that elevated glucose may contribute to the endothelial dysfunction observed in patients with diabetes mellitus.
Although compensatory islet hyperplasia in response to insulin resistance is a recognized feature in diabetes, the factor(s) that promote β cell proliferation have been elusive. We previously ...reported that the liver is a source for such factors in the liver insulin receptor knockout (LIRKO) mouse, an insulin resistance model that manifests islet hyperplasia. Using proteomics we show that serpinB1, a protease inhibitor, which is abundant in the hepatocyte secretome and sera derived from LIRKO mice, is the liver-derived secretory protein that regulates β cell proliferation in humans, mice, and zebrafish. Small-molecule compounds, that partially mimic serpinB1 effects of inhibiting elastase activity, enhanced proliferation of β cells, and mice lacking serpinB1 exhibit attenuated β cell compensation in response to insulin resistance. Finally, SerpinB1 treatment of islets modulated proteins in growth/survival pathways. Together, these data implicate serpinB1 as an endogenous protein that can potentially be harnessed to enhance functional β cell mass in patients with diabetes.
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•Elevated serpinB1 correlates with β cell proliferation in insulin resistance•SerpinB1 promotes β cell proliferation in multiple species•SerpinB1 deficiency leads to maladaptive β cell proliferation in insulin resistance•SerpinB1 inhibits elastase and activates growth/survival factor signaling pathways
Factors that promote compensatory β cell response to insulin resistance, a common feature in mammals, have been elusive. El Ouaamari et al. identify SerpinB1 as a hepatocyte-secretory protease inhibitor regulating β cell proliferation in humans, mice, and zebrafish. SerpinB1 acts by modulating canonical growth and survival signaling pathways.
Endothelium-dependent vasodilation is impaired in patients with insulin-dependent and non-insulin-dependent diabetes mellitus and restored by vitamin C administration, implicating a causative role ...for oxidant stress. Hyperglycemia per se attenuates endothelium-dependent vasodilation in healthy subjects. Accordingly, this study investigated whether impaired endothelium-dependent vasodilation caused by hyperglycemia in nondiabetic humans is restored by administration of the antioxidant vitamin C.
Endothelium-dependent vasodilation was measured by incremental brachial artery administration of methacholine chloride (0.3 to 10 microg/min) during euglycemia, after 6 hours of hyperglycemia (300 mg/dL) created by dextrose (50%) intra-arterial infusion, and with coadministration of vitamin C (24 mg/min) during hyperglycemia. Endothelium-dependent vasodilation was significantly diminished by hyperglycemia (P:=0.02 by ANOVA) and restored by vitamin C (P:=0.04). In contrast, endothelium-dependent vasodilation was not affected by equimolar infusions of mannitol, with and without vitamin C coinfusion (P:=NS). Endothelium-independent vasodilation was measured by incremental infusion of verapamil chloride (10 to 300 microg/min) without and with coadministration of N:(G)-monomethyl-L-arginine (L-NMMA). In the absence of L-NMMA, endothelium-independent vasodilation was not significantly altered during hyperglycemia (P:=NS) but was augmented by vitamin C (P:=0.04). The coadministration of L-NMMA eliminated the vitamin C-related augmentation in verapamil-mediated vasodilation.
Vitamin C administration restores endothelium-dependent vasodilation impaired by acute hyperglycemia in healthy humans in vivo. These findings suggest that hyperglycemia may contribute in part to impaired vascular function through production of superoxide anion.
Abstract Objective Higher hemoglobin A1c (HbA1c ) is associated with lower cognitive function in type 2 diabetes. To determine whether associations persist at lower levels of dysglycemia in patients ...who have established cardiovascular disease, cognitive performance was assessed in the Targeting INflammation Using SALsalate in CardioVascular Disease (TINSAL-CVD) trial. Methods The age-adjusted relationships between HbA1c and cognitive performance measured by the Mini-Mental State Examination, Digit Symbol Substitution Test, Rey Auditory Verbal Learning Test, Trail Making Test, and Categorical Verbal Fluency were assessed in 226 men with metabolic syndrome and established stable coronary artery disease. Results Of the participants, 61.5% had normoglycemia, 20.8% had impaired fasting glucose, and 17.7% had type 2 diabetes. HbA1c was associated with cognitive function tests of Digit Symbol Substitution Test, Rey Auditory Verbal Learning Test, Trail Making Test, and Categorical Verbal Fluency (all P < .02), but not the Mini-Mental State Examination. In an age-adjusted model, a 1% (11 mmol/mol) higher HbA1c value was associated with a 5.9 lower Digit Symbol Substitution Test score (95% confidence interval CI, −9.58 to −2.21; P < .0001); a 2.44 lower Rey Auditory Verbal Learning Test score (95% CI, −4.00 to −0.87; P < .0001); a 15.6 higher Trail Making Test score (95% CI, 5.73 to 25.6; P < .0001); and a 3.71 lower Categorical Verbal Fluency score (95% CI, −6.41 to −1.01; P < .02). In a multivariate model adjusting for age, education, and cardiovascular covariates, HbA1c remained associated with cognitive function tests of Rey Auditory Verbal Learning Test ( R 2 = 0.27, P < .0001), Trail Making Test ( R 2 = 0.18, P < .0001), and Categorical Verbal Fluency ( R 2 = 0.20, P < .0001), although association with the Digit Symbol Substitution Test was reduced. Conclusions Higher HbA1c is associated with lower cognitive function performance scores across multiple domain tests in men with metabolic syndrome and coronary artery disease. Future studies may demonstrate whether glucose lowering within the normative range improves cognitive health.
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