Induction of Hyperinsulinemia Combined With Hyperglycemia and Hypertriglyceridemia Increases Plasminogen Activator Inhibitor 1 in Blood in Normal Human Subjects

Abstract

Hypofibrinolysis caused by increased plasminogen activator inhibitor 1 (PAI-1) has been implicated in the vasculopathy of type 2 diabetes, typified by increased insulin, glucose, and triglycerides. However, short-term infusions of insulin have not increased PAI-1 in normal subjects. We hypothesized that induction of increased insulin accompanied by increased glucose and triglycerides would increase PAI-1. Accordingly, 30% glucose and 10% Intralipid were infused for 6 h in ten normal lean individuals (54 ± 3 years) resulting in increased insulin (42 ± 5 μU/dl), glucose (200 ± 24 mg/dl), and triglycerides (425 ± 45 mg/dl), simulating changes in type 2 diabetes. In contrast to results with infusion of saline alone (n = 16) and euglycemic-hyperinsulinemic clamps (n = 10, serum insulin = 89 ± 7 μU/dl), PAI-1 in blood increased significantly 6 h after the onset of infusion (15 ± 5 ng/ml, P <0.05 vs. baseline = 7.4± 1.1, saline 6 h = 3.4 ± 1.1, and insulin alone 6 h = 3.7 ± 0.8) and remained elevated for an additional 6 h (combined infusion = 13.8 ± 3.8 ng/ml, saline = 6.7 ± 2 ng/ml, insulin alone = 7.8 ± 1.7 ng/ml, P = 0.06). Our data suggest that combined hyperinsulinemia, hypertriglyceridemia, and hyperglycemia are likely to contribute to hypofibrinolysis of type 2 diabetes by increasing the blood levels of PAI-1. Moreover, these results underscore the potential importance of modifying insulin resistance as well as achieving glycemic and lipidemic control in individuals with type 2 diabetes.