Endocrine Abstracts

We performed this study to identify factors related to intact incretin levels in patients with type 2 diabetes (T2D). We cross-sectionally analyzed 336 patients with T2D. Intact glucagon-like peptide 1 (iGLP-1) and intact glucose-dependent insulinotropic polypeptide (iGIP) levels were measured in a fasted state and 30 min after ingestion of a standard mixed meal. The differences between 30 and 0 min iGLP-1 and iGIP levels were indicated as ΔiGLP-1 and ΔiGIP. After ingestion of a mixed meal, iGLP-1 (5.5±3.0 to 10.4±7.0 pmol/l; P<0.001) and iGIP (3.8±3.8 to 21.5±7.1 pmol/l; P<0.001) levels increased by 190% and 570%, respectively. In simple correlation analyses, fasting iGLP-1 was positively correlated with glucose (r=0.199; P<0.001), C-peptide (r=0.137; P<0.05), creatinine (r=0.124; P<0.05) and triglyceride (r=0.112; P<0.05) levels, and negatively correlated with eGFR (r=−0.139; P<0.05). ΔiGLP-1 was positively correlated only with ΔC-peptide levels (r=0.194; P<0.001). Fasting iGIP showed positive correlations with HbA1c (r=0.146; P<0.01), fasting glucose (r=0.126; P<0.05) and C-peptide (r=0.153; P<0.01) levels, and negative correlations with ΔC-peptide (r=−0.183; P<0.01) and HDL cholesterol (r=−0.124; P<0.05) levels. ΔiGIP was negatively correlated with diabetes duration (r=−0.118; P<0.05) and HbA1c (r=−0.196; P<0.001) levels, and positively correlated with ΔGlucose (r=0.210; P<0.001) and ΔC-peptide (r=0.238; P<0.01) levels. In multivariate analyses adjusting for age, sex, and covariates, fasting iGLP-1 levels were significantly related to fasting glucose (β=0.189, P<0.01) and creatinine (β=0.158, P<0.05) levels, ΔiGLP-1 levels were positively related to ΔC-peptide levels (β=0.194, P<0.001), fasting iGIP levels were related to fasting C-peptide levels (β=0.160, P<0.01) and female sex (β=0.124, P<0.05), and ΔiGIP levels were positively related to ΔC-peptide (β=0.165, P<0.01) and Δglucose (β=0.138, P<0.05) levels. Taken together, intact incretin levels are primarily related to C-peptide and glucose levels. This result suggests that glycemia and insulin secretion are the main factors associated with intact incretin levels in T2D patients.