Two nights of recovery sleep restores the dynamic lipemic response, but not the reduction of insulin sensitivity, induced by five nights of sleep restriction

Chronic inadequate sleep is associated with increased risk of cardiometabolic diseases. The mechanisms involved are poorly understood but involve changes in insulin sensitivity, including within adipose tissue. The aim of this study was to assess the effects of sleep restriction on nonesterified fatty acid (NEFA) suppression profiles in response to an intravenous glucose tolerance test (IVGTT) and to assess whether 2 nights of recovery sleep (a “weekend”) is sufficient to restore metabolic health. We hypothesized that sleep restriction impairs both glucose and lipid metabolism, specifically adipocyte insulin sensitivity, and the dynamic lipemic response of adipocyte NEFA release during an IVGTT. Fifteen healthy men completed an inpatient study of 3 baseline nights (10 h of time in bed/night), followed by 5 nights of 5 h of time in bed/night and 2 recovery nights (10 h of time in bed/night). IVGTTs were performed on the final day of each condition. Reductions in insulin sensitivity without a compensatory change in acute insulin response to glucose were consistent with prior studies (insulin sensitivity P = 0.002; acute insulin response to glucose P = 0.23). The disposition index was suppressed by sleep restriction and did not recover after recovery sleep ( P < 0.0001 and P = 0.01, respectively). Fasting NEFAs were not different from baseline in either the restriction or recovery conditions. NEFA rebound was significantly suppressed by sleep restriction ( P = 0.01) but returned to baseline values after recovery sleep. Our study indicates that sleep restriction impacts NEFA metabolism and demonstrates that 2 nights of recovery sleep may not be adequate to restore glycemic health.

Sucralose decreases insulin sensitivity in healthy subjects: a randomized controlled trial

ABSTRACT Background Recently, the absence of metabolic effects from nonnutritive sweeteners has been questioned. Objective The aim of this study was to evaluate the effects of sucralose consumption on glucose metabolism variables. Design We performed a randomized controlled trial involving healthy subjects without comorbidities and with a low habitual consumption of nonnutritive sweeteners (n = 33/group). Methods The intervention consisted of sucralose consumption as 15% of Acceptable Daily Intake every day for 14 d using commercial sachets. The control group followed the same procedures without any intervention. The glucose metabolism variables (insulin sensitivity, acute insulin response to glucose, disposition index, and glucose effectiveness) were evaluated by using a 3-h modified intravenous-glucose-tolerance test before and after the intervention period. Results Individuals assigned to sucralose consumption showed a significant decrease in insulin sensitivity with a median (IQR) percentage change of −17.7% (−29.3% to −1.0%) in comparison to −2.8% (−30.7% to 40.6%) in the control group (P= 0.04). An increased acute insulin response to glucose from 577 mU · L-1· min (350–1040 mU · L-1· min) to 671 mU · L-1· min (376–1010 mU · L-1· min) (P = 0.04) was observed in the sucralose group for participants with adequate adherence. Conclusions Sucralose may have effects on glucose metabolism, and our study complements findings previously reported in other trials. Further studies are needed to confirm the decrease in insulin sensitivity and to explore the mechanisms for these metabolic alterations. This trial was registered at www.clinicaltrials.gov as NCT02589002.