Mechanism by which high-dose aspirin improves glucose metabolism in type 2 diabetes

Abstract

Recent studies have implicated fatty acid-dependent activation of the serine kinase IKKbeta, which plays a key role in tissue inflammation, in the pathogenesis of insulin resistance. High doses of salicylates have recently been shown to inhibit IKKbeta activity and might therefore ameliorate insulin resistance and improve glucose tolerance in patients with type 2 diabetes. To test this hypothesis, we studied nine type 2 diabetic subjects before and after 2 weeks of treatment with aspirin ( approximately 7 g/d). Subjects underwent mixed-meal tolerance tests and hyperinsulinemic-euglycemic clamps with [6,6-(2)H2]glucose to assess glucose turnover before and after treatment. High-dose aspirin treatment resulted in a approximately 25% reduction in fasting plasma glucose, associated with a approximately 15% reduction in total cholesterol and C-reactive protein, a approximately 50% reduction in triglycerides, and a approximately 30% reduction in insulin clearance, despite no change in body weight. During a mixed-meal tolerance test, the areas under the curve for plasma glucose and fatty acid levels decreased by approximately 20% and approximately 50%, respectively. Aspirin treatment also resulted in a approximately 20% reduction in basal rates of hepatic glucose production and a approximately 20% improvement in insulin-stimulated peripheral glucose uptake under matched plasma insulin concentrations during the clamp. In conclusion, these data support the hypothesis that IKKbeta represents a new target for treating type 2 diabetes mellitus.

Figure 1

Mean plasma concentrations of glucose (a), insulin (b), and C-peptide (c) during mixed-meal tolerance testing.

Figure 2

(a) Rates of glucose metabolism before and after aspirin treatment. EGP, endogenous glucose production; GIR, glucose infusion rate during the clamp; cEGP, endogenous glucose production during the clamp; Rd, glucose disposal rate during the clamp; OX, glucose oxidation rates. *P = 0.009, **P = 0.003 vs. base-line. (b) Mean plasma insulin concentrations during the hyperinsulinemic-euglycemic clamp.

Figure 3

(a) Rates of glucose metabolism in a subgroup of six subjects for the post-aspirin and matched insulin studies. (b) Mean plasma insulin concentrations for the two studies in the same subgroup of subjects.