The Impact of Dopamine on Insulin Secretion in Healthy Controls.

OBJECTIVE: Dopamine is very commonly used in the critical care setting and impacts glucose homeostasis. In some studies, it is noted to increase insulin resistance or decrease insulin secretion. The role of insulin secretion in response to dopamine is incompletely understood. METHODS: Eight individuals underwent a hyperglycemic clamp with a dopamine infusion, and eight controls underwent hyperglycemic clamp alone. Insulin, C-peptide, glucagon, cortisol, and norepinephrine (NE) concentrations were measured at various time points. An index of insulin sensitivity (M/I) was calculated. Statistical comparison between the control and treatment arm was done using repeated measures ANOVA. The data is expressed as mean ± standard deviation. Paired t-test was used to compare pre- and post-dopamine infusion time points in the study individuals only. Data was considered to be statistically significant at P < 0.05. RESULTS: On assessing the treatment group before and during dopamine infusion, insulin and C-peptide concentrations were higher at the time of the infusion (P = 0.02 and P = 0.003, respectively). The index of insulin sensitivity was not statistically different. There was a significant decrease in insulin (P = 0.002), C-peptide (P = 0.005), and NE (P < 0.0001) concentrations in the treatment group, compared to the controls. Glucagon concentration was higher in the treatment group (P = 0.02). CONCLUSION: In this study, dopamine infusion did not adversely impact insulin secretion.

Insulin sensitivity and obstructive sleep apnea in adolescents with polycystic ovary syndrome.

BACKGROUND: Polycystic ovary syndrome (PCOS) in adults is linked with insulin resistance (IR) and obstructive sleep apnea (OSA). However, less is known about these associations in adolescents. METHODS: We studied 3 groups of adolescents: 27 obese PCOS (OPCOS) (ages 13-21)11 normal-weight PCOS (NPCOS) (ages 13-21 years), and 8 healthy controls (ages 18-21 years). A hyperinsulinemic euglycemic clamp study was performed in all groups to determine IR by insulin sensitivity (M/I). Polysomnography was performed to assess for OSA in OPCOS and NPCOS groups. We compared indices of IR among all groups and OSA among OPCOS, and NPCOS. RESULTS: We noted that OPCOS and NPCOS and controls differed significantly in their IR. M/I was significantly lower in OPCOS vs. controls (p=0.0061), and also lower for NPCOS vs control but this approached but did not reach statistical significance (p=0.084). In addition, none of the NPCOS subjects had OSA compared to 42% of OPCOS (p=0.03). CONCLUSIONS: Our study suggests OPCOS adolescents have increased IR compared to controls and NPCOS subjects. Higher IR for NPCOS vs controls approached but did not reach statistical significance. Larger studies are needed. In addition, adolescents with OPCOS are at a high risk for OSA.

The impact of weight change and measures of physical functioning on mortality.

INTRODUCTION: Lower grip strength and measures of physical functioning are associated with all-cause mortality. Relationships among long-term weight loss, physical functioning, and mortality in older women are understudied. METHODS: Participants were 5039 women who were part of the Long Life Study (LLS) ancillary study to the Woman's Health Initiative (WHI). Average age was 78.76 ± 6.92. We defined long-term weight loss or gain as a decrease or increase of 5% or more of baseline body weight. Our primary outcome was all-cause mortality and our secondary outcomes were vascular death, and coronary heart disease (CHD). The mean follow-up time was 5.4 years. Cox regression modeling was performed for each outcome of interest. Variables of interest were weight change, grip strength, and functional status as measured by the Short Physical Performance Battery (SPPB) controlling for multiple potential confounders. RESULTS: Weight loss of 5% or more percent body weight was associated with a hazard ratio of 1.66 (1.37-2.01) for all-cause mortality. Weight gain was not related to mortality or cardiovascular outcomes. Those in the highest grip strength quartile had a hazard ratio of 0.51 (0.39-0.66) for all-cause mortality. For the SPPB the hazard ratio was 0.29 (0.21-0.40), adjusting for changes in weight, race, smoking, history CHD, smoking, and diabetes. Higher grip strength and SPPB were associated with lower risks for vascular death, and CHD, independently of weight change. CONCLUSIONS: Weight loss was associated with increased mortality. Stronger grip strength and higher SPPB scores were associated with lower mortality risk independent of weight change.

Use of Sitagliptin With Closed-Loop Technology to Decrease Postprandial Blood Glucose in Type 1 Diabetes.

BACKGROUND: Postprandial hyperglycemia poses a challenge to closed-loop systems. Dipeptidyl peptidase-4 (DPP-4) inhibitors, like sitagliptin, reduce postprandial glucose concentrations in patients with type 2 diabetes. The objective of this study was to assess sitagliptin's role in type 1 diabetes (T1DM) as an adjunct therapy in reducing postprandial blood glucose with an insulin-only closed-loop system. METHODS: This was a randomized, double-blinded, placebo controlled, crossover design trial. The participants were18-35 years old, had T1DM, and an HbA1c of ≤ 8.5%. A dose determination study included eight subjects with T1DM. There were three study visits. Four hours after receiving study drug (placebo, sitagliptin 50 mg, sitagliptin 100 mg), subjects underwent a mixed meal tolerance test with assessment of hormone concentrations. In a second study, 15 subjects underwent two visits receiving either placebo or 100 mg of sitagliptin plus an insulin only closed-loop system for 25 hours with timed meals. Blood glucose and other hormone concentrations were analyzed using repeated measures ANOVA. RESULTS: For the dose determination study, sitagliptin 100 mg resulted in reduced postprandial blood glucose ( P = .006). For the closed-loop study, glucose concentrations were lower in the treatment group, most prominently during the first two study meals ( P = .03). There was no difference in glucagon concentrations, but insulin concentrations and insulin delivery were lower in the treatment group. CONCLUSIONS: Sitagliptin may be considered as an adjunct therapy in a closed-loop setting. Larger studies are needed to determine the role of oral agents like sitagliptin to lower postprandial hyperglycemia with closed loop.

A Case of Thyroid Storm Associated with Cardiomyopathy and Poststreptococcal Glomerulonephritis.

Thyroid storm has a high mortality rate and is often associated with a precipitating factor such as intercurrent illness or infection. It is rare in pediatric patients. Cardiac disease in hyperthyroidism mostly manifests itself as tachycardia but more serious cardiac findings have also been described. A 5-year-old male with recent strep throat infection presented with dilated cardiomyopathy, hematuria, and symptoms and lab findings consistent with severe hyperthyroidism. He was diagnosed with thyroid storm secondary to concurrent Graves' disease and poststreptococcal glomerulonephritis (PSGN). After starting the treatment with methimazole and a beta-blocker, his cardiac disease gradually improved and the PSGN resolved over time. There are no specific pediatric criteria for thyroid storm. Adult criteria can be difficult to apply to pediatric cases. Criteria for diagnosis of thyroid storm are less clear for pediatric patients. Dilated cardiomyopathy is a rare cardiac manifestation of hyperthyroidism. PSGN is due to glomerular immune complexes and can complicate group A strep infection. Providers should be aware of cardiac disease as a complication of hyperthyroidism. PSGN should not mechanistically be related to hyperthyroidism but can precipitate the signs of thyroid storm such as hypertension. This association has not been previously reported in the literature.