224-OR: Diurnal Pattern of Insulin Action and Beta-Cell Function in Health and Type 2 Diabetes

Abstract

We have previously reported differences in insulin sensitivity (SI) between T1D and nondiabetic (ND) subjects throughout the day. To explore differences in the diurnal pattern of SI, beta-cell responsivity to glucose (Φ) and disposition index (DI) between type 2 diabetes (T2D) and ND subjects, we present novel preliminary data from 5 ND (BMI 26.6±1.8 kg/m2, age 62.6±4.8 years, Mean±SE) and 5 T2D subjects (BMI 33.6±2.4 kg/m2, age 60.0±6.0 years, HbA1c 55±11 mmol/mol). Studies were conducted in the Clinical Research Unit. Subjects ingested identical mixed meals (75 g carbs, 55% carbohydrate, 15% protein, 30% fat) at either breakfast (B), lunch (L) or dinner (D) in randomized Latin Square order on three consecutive days. Plasma glucose (G), insulin (I) and C-peptide (C) concentrations were frequently sampled. Oral glucose and C-peptide minimal models were applied to estimate SI, Φ and DI. Differences among B, L and D and between ND and T2D were assessed by two-way ANOVA (a p-value <0.05 was considered statistically significant). The emerging patterns suggest that SI, Φ and DI were lower in T2D than ND (Figure 1) subjects throughout the day. While SI steadily decreased in T2D, it was variable in ND subjects as the day progressed. DI was significantly lower in T2D at dinner than at Breakfast. The data to date indicate that the diurnal patterns of insulin action and beta cell function differ between ND and T2D subjects through the day. Disclosure D. Romeres: None. M. Schiavon: None. C. Cobelli: None. C. Dalla Man: None. A. Basu: Research Support; Spouse/Partner; AstraZeneca. R. Basu: Other Relationship; Self; AstraZeneca. Funding National Institutes of Health (R01029953)