1832-P: Impact of Habitual Daily Activity on Glucose Tolerance (GT) and ß-Cell Function in Adults with Impaired GT (IGT) or Type 2 Diabetes (T2D)

We examined the relationship between habitual daily activity and measures of GT, insulin sensitivity and β-cell responses in 230 adults (mean age 55 y; BMI 35 kg/m²) with IGT or drug-naïve, recently diagnosed T2D. Participants underwent a 3-h OGTT and hyperglycemic clamp. Wrist accelerometers worn for 7 days measured total activity counts (TAC; daily mean 233,461 {∼ 50th %ile for age}). We evaluated whether TAC predicted fasting plasma glucose (FPG); OGTT 2-h plasma glucose (2-h G) or glucose incremental area under the curve (G-iAUC); hyperglycemic clamp measures of insulin sensitivity (steady-state glucose infusion rate/insulin [M/I]) and β-cell responses (acute C-peptide response to glucose [ACPRg], steady-state C-peptide, maximal β-cell response [ACPRmax]); and OGTT C-peptide index (CPI, [ΔC-Peptide_0-30/ΔGlucose_0-30]). There was no association of TAC with FPG, 2-h G, or G-iAUC. Higher TAC was associated with higher insulin sensitivity. After adjusting for M/I, higher TAC was associated with lower CPI, but not with clamp-based β-cell responses. Despite similar post-load glucose values, adults with IGT or T2D who were more active demonstrated a greater than expected reduction in C-peptide response given their higher insulin sensitivity. Further studies are needed to understand this dissociation of activity effects on insulin sensitivity and β-cell function.