Acute effects of hyperinsulinemia and hyperglycemia on vascular inflammatory biomarkers and endothelial function in overweight and obese humans

Abstract

We investigated the separate and combined effects of hyperglycemia and hyperinsulinemia on markers of endothelial function, proinflammatory and proatherothrombotic responses in overweight/obese nondiabetic humans. Twenty-two individuals (13 F/9 M, BMI 30.1 ± 4.1 kg/m(2)) were studied during four randomized, single-blind protocols. The pancreatic clamp technique was combined with 4-h glucose clamps consisting of either 1) euinsulinemia-euglycemia, 2) euinsulinemia-hyperglycemia, 3) hyperinsulinemia-hyperglycemia, or 4) hyperinsulinemia-euglycemia. Insulin levels were higher (998 ± 66 vs. 194 ± 22 pmol/l) during hyperinsulinemia compared with euinsulinemia. Glucose levels were 11.1 mmol/l during hyperinsulinemia compared with 5.1 ± 0.1 mmol/l during euglycemia. VCAM, ICAM, P-selectin, E-selectin, IL-6, adiponectin, and PAI-1 responses were all increased (P < 0.01-0.0001), and endothelial function was decreased (P < 0.0005) during euinsulinemia-hyperglycemia compared with other protocols. Hyperinsulinemia in the presence of hyperglycemia prevented the increase in proinflammatory and proatherothrombotic markers while also normalizing vascular endothelial function. We conclude that 4 h of moderate hyperglycemia can result in increases of proinflammatory markers (ICAM, VCAM, IL-6, E-selectin), platelet activation (P-selectin), reduced fibrinolytic balance (increased PAI-1), and disordered endothelial function in a group of obese and overweight individuals. Hyperinsulinemia prevents the actions of moderate hyperglycemia to reduce endothelial function and increase proinflammatory and proatherothrombotic markers.

Keywords: endothelial function; hyperglycemia; hyperinsulinemia; inflammation.

Copyright © 2015 the American Physiological Society.

Figures

Fig. 1.

Experimental protocols.

Fig. 2.

Glucose and insulin values in 23(14 F/9 M) adult healthy volunteers during euglycemic (5.0 mmol/l) and hyperglycemic (11.1 mmol/l) glucose clamps in the presence of octreotide and insulin infused at either 1.8 or 9 pmol·kg−1·min−1.

Fig. 3.

Timeline responses from baseline of adiponectin, ICAM, P-selectin, IL-6, E-selectin, PAI-1, and VCAM during euglycemic (5.0 mmol/l) and hyperglycemic (11.1 mmol/l) clamps in the presence of octreotide and insulin at 1.8 or 9 pmol·kg−1·min−1 in overnight-fasted obese/overweight humans. *Response during euinsulinemic hyperglycemia is significantly increased (P < 0.01-0.0001) vs. responses in the other groups. †Response is significantly decreased (P < 0.02-0.0001) vs. baseline. #Response is significantly increased (P < 0.02-0.0001) vs. baseline.

Fig. 4.

Responses at baseline and end of clamp flow-mediated (endogenous) and nitroglycerin (exogenous) -mediated dilation during euglycemic (5.0 mmol/l) and hyperglycemic clamps (11.1 mmol/l) in the presence of octreotide and insulin infused at 1.8 or 9 pmol·kg−1·min−1 in overnight-fasted obese/overweight humans. *Response is significantly (P < 0.01) different from baseline. ≠Response of mean maximal %change is significantly (P < 0.01-0.001) different from euinsulinemia-euglycemia.