Adiposity Markers Are Related to Insulin Sensitivity and Secretion Measured during OGTT

Introduction and Objective: People with excess weight have a different susceptibility to type 2 diabetes. Underlying mechanisms explaining those differences are still a matter of debate. Our aim was to determine whether insulin sensitivity and secretion could be related to a spectrum of metabolic parameters. Methods: The subjects were healthy volunteers or patients with overweight/obesity seeking nutritional assessment. We studied 66 subjects (36 (55%) females, median (IQR) age 48.5 (29, 56) years) with a modified oral glucose tolerance test (OGTT), dosing glucose, insulin, and C-peptide every 30 minutes along a 3-hour period and estimating insulin sensitivity and secretion from OGTT-derived parameters through a model-based method. Anthropometric and fasting biochemical parameters were also measured. Results: Our sample had a median (IQR) BMI of 26.16 (23.37, 29.75) kg/m2, with a fat mass percentage of 34.1 (26.6, 39.6) %. After adjusting for sex, age, and BMI, we found a negative relationship between insulin sensitivity during OGTT (OGIS index), ultrasound-measured visceral adipose tissue (-1.18; 95% CI -2.26,-0.10), fatty liver index (-1.36; 95% CI -2.12, -0.60), and triglycerides (-0.38; 95% CI -0.70, -0.06) (all p<0.05); conversely, fasting HOMA-IR was associated only with visceral adipose tissue (+0.05; 95% CI 0.01, 0.09) and triglycerides (+0.02; 95% CI 0.01, 0.03) (all p<0.05). Additionally, a positive relationship was found between total insulin secretion and visceral adipose tissue (0.44; 95% CI 0.10, 0.77), fatty liver index (0.48; 95% CI 0.01, 0.95), and triglycerides (0.20; 95% CI 0.07, 0.33) (all p<0.05). Conclusion: In conclusion, we have shown that OGTT-derived OGIS index is more informative on metabolic status than fasting HOMA-IR and that visceral adipose tissue and fatty liver index are significantly related to OGTT-derived parameter indicating insulin secretion. Disclosure F. Sileo: None. A. Mari: Consultant; Lilly USA LLC, Novo Nordisk, Sanofi. A. Foppiani: None. G. Pozzi: None. S. Gallosti: None. A. Battezzati: None.