Association between plasma glucose-dependent insulinotropic polypeptide and active adiponectin in normoglycemic women.

Background/objectives: Glucose-dependent insulinotropic polypeptide (GIP) is secreted by enteroendocrine K cells in response to nutrient ingestion. The aims of this study were: i) to evaluate the cross-sectional associations between plasma GIP change in response to an oral glucose challenge (as a surrogate of GIP secretion) with obesity-related anthropometric measurements, fasting inflammatory biomarkers, and fasting circulating adipokines; and ii) to evaluate the feasibility of using postprandial plasma GIP as a biomarker of adiposity-related phenotypes in response to starch-based meals. Methods: Fifty normoglycemic women without obesity (19-32 years) were evaluated with an oral glucose tolerance test (OGTT). A feasibility study was conducted in a subset of eight women to estimate responses to starch-based meals (25 g of starch). Postprandial glycemic-related changes in plasma hormones/metabolites were assessed, and circulating adipokines and inflammatory biomarkers in fasting conditions. Results: The incremental-GIP change after 2 h OGTT was significantly associated with waist circumference (rho = 0.34; P = 0.02), fasting plasma TNF-α (rho = 0.54; P = 0.0002), and white blood cell count (rho = 0.39; P = 0.008), but not with MCP-1, total adiponectin, leptin, or the free leptin index. A strong inverse association was found between incremental-GIP change and fasting plasma high-molecular-weight (HMW) adiponectin (rho = -0.50; P = 0.0004), which remained significant after adjusting for age and body mass index. Conclusion: An inverse association was found between postprandial GIP levels and circulating HMW-adiponectin levels in humans. This work highlights the suitability of using postprandial plasma GIP as a biomarker for metabolic disturbances of increased adiposity, even in the absence of obesity.