Effect of 8 hours of hyperinsulinaemia on haemostatic parameters in healthy man

Abstract

Summary.The role of variations in plasma insulin concentrations as a factor possibly involved in abnormalities of haemostatic functions, and (or) the development of arterial disease, has been the subject of controversy. This study examines the "in vivo" effect of hyperinsulinaemia on haemostatic parameters in seven healthy men. Two studies were carried out in random order: (a) Hyperinsulinaemia study. Human insulin was infused by a calibrated infusion pump (0.7 mU kg -1 rain -~, for 8 h) during a euglycaemic glucose clamp, and (b) Control study 0.15 mmol/1 NaC1 solution was infused over 8 h. Plasma epinephrine and norepinephrine concentrations remained constant throughout the studies. Mean insulin levels during the hyperinsulinaemia study were 46.2__+ 1.6 9U/ml, i.e. approximately eightfold higher than those at baseline, whereas plasma glucose levels remained constant at 4.9 + 0.1 mmol/1. During the control study, mean insulinaemia was 5.0+ 0.9 gU/ml, and plasma glucose 5.2 + 0.1 retool/1. No statistically significant changes were observed ,during, or after insulin or 0.15 retool/1 NaC1 infusions with regard to platelet parameters, blood coagulation, and coagulation inhibitors. These data suggest that abnormalities of the haemostatic function described during insulin-induced hypoglycaemia or in hyperinsulinaemic patients are not due to a direct action of insulin.Key words: Haemostasis, hyperinsulinaemia, platelet function.Arterial disease affecting both large and small calibre vessels is responsible for the major causes of the increased morbidity and mortality in diabetic patients. Considerable efforts have been made to identify the role of the haemostatic system as a factor possibly involved in the pathogenesis of vascular complications in diabetic subjects during hyperglycaemic, normoglycaemic, and hypoglycaemic conditions [1][2][3][4]. Multiple abnormalities of haemostatic functions during insulininduced hypoglycaemia have been described; including increased platelet aggregation, alterations of coagulation factors and abnormal fibrinolytic activity [5][6][7][8][9][10][11][12]. These haemostatic dysfunctions have either been attributed to acute hyperinsulinaemia or the secondary increases of counter r~gulatory hormone concentrations [5,7, 11].On the other hand, several studies have shown that obesity is associated both with alterations of haemostatic functions and hyperinsulinaemia [13]: In addition, it has been shown that patients with hypertension are hyperinsulinaemic, independent of concomitant obesity or antihypertensive medication, and present with haemostatic abnormalities [14,15]. Recent reports have suggested that hyperinsulinaemia may be a possible risk factor for macrovascular disease in diabetes mellitus, and that hyperinsulinaemia may relate to cardiovascular disease independent of other risk factors [16,17].The role of variation in plasma insulin concentration as a factor possibly involved in abnormalities of haemostatic function and (or) the development of arterial disease is unknown. The purpos...

Mechanisms of Arterial Hypotension After Therapeutic Dose of Subcutaneous Insulin in Diabetic Autonomic Neuropathy

“…First, insulin activates the SNS. In humans, some studies (35)(36)(37) have reported no effects of hyperinsulinemia on plasma NE concentration, but the majority of studies (7,13,15,18,19,21,(38)(39)(40)(41)(42)(43)(44)(45) have found an effect. Second, therapeutic hyperinsulinemia markedly blunts the vasoconstrictive responses to activation of the SNS in the standing position.…”

The sympathetic response to euglycaemic hyperinsulinaemia

“…Elevation of plasma insulin to a mean steadystate level of 46 mU/1 [22] or 100-200 mU/1 failed to elevate plasma catecholamines [23,24], whereas other investigations have found minor but significant elevations of plasma noradrenaline at plasma insulin concentrations ranging from a level corresponding to postprandial hyperinsulinaemia in normal and insulin-resistant subjects, i. e. less than 100 mU/1 [25] to supraphysiological levels [6,7,26]. The occasional failure to observe increases in plasma noradrenaline may be methodological, as moderate hyperinsulinaemia is apparently a weak sympathetic stimulus.…”

Circulating catecholamines and metabolic effects of captopril in NIDDM patients

“…Indeed, plasma NE concentrations failed to increase during mild hyperinsulinemia in both normal (27) and diabetic subjects (28,29), while a significant elevation has been reported in both nonobese (30)(31)(32) and obese men (33) when insulin was infused at higher doses. Indeed, plasma NE concentrations failed to increase during mild hyperinsulinemia in both normal (27) and diabetic subjects (28,29), while a significant elevation has been reported in both nonobese (30)(31)(32) and obese men (33) when insulin was infused at higher doses.…”