Early time-restricted carbohydrate consumption vs conventional dieting in type 2 diabetes: a randomised controlled trial.

AIMS/HYPOTHESIS: Early time-restricted carbohydrate consumption (eTRC) is a novel dietary strategy that involves restricting carbohydrate-rich food intake to the morning and early afternoon to align with circadian variations in glucose tolerance. We examined the efficacy, feasibility and safety of eTRC in individuals with type 2 diabetes under free-living conditions. METHODS: In this randomised, parallel-arm, open label, controlled trial, participants with type 2 diabetes and overweight/obesity (age 67.2±7.9 years, 47.8% women, BMI 29.4±3.7 kg/m2, HbA1c 49±5 mmol/mol [6.6±0.5%]) were randomised, using computer-generated random numbers, to a 12 week eTRC diet or a Mediterranean-style control diet with matched energy restriction and macronutrient distribution (50% carbohydrate, 30% fat and 20% protein). The primary outcome was the between-group difference in HbA1c at 12 weeks. Body composition, 14 day flash glucose monitoring and food diary analysis were performed every 4 weeks. Mixed meal tolerance tests with mathematical beta cell function modelling were performed at baseline and after 12 weeks. RESULTS: Twelve (85.7%) participants in the eTRC arm and 11 (84.6%) participants in the control arm completed the study, achieving similar reductions in body weight and fat mass. The two groups experienced comparable improvements in HbA1c (-3 [-6, -0.3] mmol/mol vs -4 [-6, -2] mmol/mol, corresponding to -0.2 [-0.5, 0]% and -0.3 [-0.5, -0.1]%, respectively, p=0.386), fasting plasma glucose, flash glucose monitoring-derived glucose variability and mixed meal tolerance test-derived glucose tolerance, insulin resistance, insulin clearance and plasma glucagon levels, without changes in model-derived beta cell function parameters, glucagon-like peptide-1, glucose-dependent insulinotropic polypeptide and non-esterified fatty acid levels. The two diets similarly reduced liver function markers and triglyceride levels, being neutral on other cardiometabolic and safety variables. In exploratory analyses, diet-induced changes in body weight and glucometabolic variables were not related to the timing of carbohydrate intake. CONCLUSIONS/INTERPRETATION: The proposed eTRC diet provides a feasible and effective alternative option for glucose and body weight management in individuals with type 2 diabetes, with no additional metabolic benefits compared with conventional dieting. TRIAL REGISTRATION: ClinicalTrials.gov NCT05713058 FUNDING: This study was supported by the European Society for Clinical Nutrition and Metabolism (ESPEN) and the Italian Society of Diabetology (SID).

Circadian heart rate fluctuations predict cardiovascular and all-cause mortality in type 2 and type 1 diabetes: a 21-year retrospective longitudinal study.

BACKGROUND: Circadian heart rate (HR) fluctuations are associated with cardiovascular health. We examined their relationship with microvascular disease and long-term survival in patients with diabetes. METHODS: In this secondary analysis from the CHAMP1ON cohort of 497 adults with metabolic disease, 349 participants who had type 1 or type 2 diabetes, baseline 24h ambulatory blood pressure and HR monitoring (ABPM), and survival data over a 21-year observational follow-up were included. Clinical features, microvascular complications, and mortality rates were examined in participants with low circadian HR fluctuations (24h-HR SD below the median of 30.4) and blunted nocturnal HR dip (<10%). RESULTS: Low 24h-HR SD and blunted nocturnal HR dip were associated with an adverse cardiometabolic risk profile and 12-23% higher prevalence of cardiac autonomic neuropathy and nephropathy. After 6,251 person-years follow-up (21.0 [14.0-21.0] years), a total of 136 (39%) deaths occurred, of which 100 (68%) of cardiovascular cause. The low 24h-HR SD group had a higher risk for both cardiovascular (adjusted hazard ratio [aHR] 2.00, 95%CI 1.30-3.08, p=0.002) and all-cause mortality (aHR 1.61, 95%CI 1.13-2.29, p=0.009), compared with high 24h-HR SD. Similarly, patients with blunted nocturnal HR dip had a higher risk for cardiovascular (aHR 1.63, 95%CI 1.08-2.46, p=0.019) and all-cause mortality (aHR 1.69, 95%CI 1.20-2.38, p=0.003), compared with those with preserved nocturnal HR dip. CONCLUSIONS: Impaired circadian HR fluctuations are associated with microvascular disease and long-term cardiovascular and all-cause mortality in diabetes. ABPM-derived HR measures may provide a widely available and inexpensive risk stratification tool in this high-risk population.

Circadian heart rate (HR) fluctuations are associated with cardiovascular health. We examined their relationship with microvascular disease and long-term survival in patients with diabetes. Impaired HR fluctuations measured by 24h ambulatory blood pressure and HR monitoring (ABPM) were associated with an adverse cardiometabolic risk profile, higher prevalence of cardiac autonomic neuropathy and nephropathy, and higher risk for cardiovascular and all-cause mortality over a 21-year follow-up. ABPM-derived HR measures may provide a cost-effective risk stratification tool in this high-risk population.