Effect of aprotinin on insulin sensitivity in non-insulin-dependent diabetes mellitus

It has been suggested that kallikrein-kinin system may influence carbohydrate metabolism via a kinin-mediated increment of insulin-mediated glucose uptake. To evaluate the effect of acute inhibition of the kallikrein-kinin system on insulin sensitivity, a randomized, placebo-controlled, double-blind study was performed in 15 male non-insulin-dependent diabetic patients. After basal evaluation of insulin sensitivity with a 2-h euglycaemic hyperinsulinaemic clamp (40 mU m(-2) min(-1)), patients were infused either with aprotinin (200 000 U.I.C. as intravenous bolus injection) or placebo (10 ml isotonic saline) in a cross-over fashion, at 1 week intervals. After both saline and aprotinin infusions, insulin sensitivity was reassessed by continuing the euglycaemic hyperinsulinaemic clamp for a further 1 h. Resulting data showed that aprotinin significantly improved total glucose uptake (from 16.2 +/- 2.9 mu mol kg min(-1) to 20.6 +/- 4.9 mu mol kg min(-1), p<0.01), and decreased metabolic clearance rate of insulin (from 586 +/- 57 ml m(-2) min(-1) to 442 +/- 155 ml m(-2) min(-1), p<0.05). Thus, in spite of the suggested positive effects of kinins on insulin-mediated glucose uptake, acute inhibition of the kallikrein-kinin system resulted in a paradoxical increment of insulin sensitivity, which was probably mediated by the reduced metabolic clearance rate of insulin.