Abstract 817: Glucose Loading Increases Adiponectin Levels in Subjects With Impaired Glucose Tolerance and Impairs Endothelial Function
Background: Adiponectin is an adipokine with beneficial effect on vascular function. Although adiponectin levels are decreased in patients with diabetes mellitus (DM), it is unclear whether impaired glucose tolerance (IGT) affects adiponectin’s release, or whether glucose intake modifies its release from adipocytes. We examined the effect of glucose on serum adiponectin/insulin and endothelial function, in subjects with IGT, patients with DM and healthy individuals.
Methods: The study population consisted of 113 subjects: 19 with IGT, 78 with DM and 16 controls. All subjects underwent glucose loading (75g oral glucose), and blood samples were obtained at baseline and after 3 hours. Endothelial function was evaluated by gauge-strain plethysmography at baseline and every 1h, and endothelium-dependent dilation (EDD) was determined. Adiponectin and insulin were measured at baseline and at 3h.
Results: Glucose loading increased adiponectin levels in healthy (70.1±8.5 to 80.8±11.4 ng/ml, p<0.05) and IGT (52.6±4.5 to 61.3±6.5 ng/ml p<0.05) but not in DM (55.9±3.5 to 56.8±3.5 ng/ml). Although insulin was correlated with adiponectin both at baseline (r=−0.375, p=0.0001) and at 3h (r=−0.286, p=0.006), insulin variations did not follow the same pattern (healthy: 6.55±0.65 to 9.25±1.17 IU/L p<0.05, IGT:11.6±2.7 to 17.6±4.9IU/L p<0.05, and DM: 10.24±0.89 to 20.99±2.37 IU/L p<0.0001). There was no association between the changes of insulin and those of adiponectin (p=NS). EDD was decreased after loading in healthy (from 76.6±5.2% to 63.0±6.6%, 57.0±6.5% and 89.3±6.3% for 0h, 1h, 2h and 3h, p<0.05 for 0h vs 2h), in IGT (from 92.8±6.4% to 66.9±6.1%, 68.6±6.8% and 85.6±6.1% for 0h, 1h, 2h and 3h, p<0.01 for 0h vs 2h) and DM (from 86.1±5.1% to 60.7±2.4%, 54.6±2.3% and 75.2±2.8% for 0h, 1h, 2h and 3h, p<0.01 for 0h vs 1h, 2h and p<0.05 vs 3h).
Conclusions: Glucose intake increases serum adiponectin in healthy individuals and subjects with impaired glucose tolerance, but not in those with DM. This effect is independent of insulin variations. Glucose impairs endothelial function, an effect which is more profound in patients with DM. These findings provide new insights into the associations between insulin, adiponectin and endothelial function in diabetes mellitus.