Influence of proteinuria on vascular disease, blood pressure, and lipoproteins in insulin dependent diabetes mellitus.

Patients with insulin dependent diabetes mellitus who develop proteinuria may die prematurely, whereas those who do not develop this complication have a comparatively normal life span. The excess mortality in diabetics with proteinuria is from cardiovascular as well as renal disease, but the reason is unclear. Risk factors for vascular disease were therefore assessed in 22 insulin dependent diabetics with proteinuria, but not renal failure, who were matched for sex, age, duration of diabetes, and glycated haemoglobin (HbA1) values with a similar number who had normal urinary albumin excretion rates. Macrovascular disease (ischaemic heart disease and peripheral vascular disease) was present in 10 patients with proteinuria but in only three with normal albumin excretion rates, and proliferative retinopathy was detected in 11 and four patients in the two groups. There was no significant excess of smokers in the group with proteinuria. Blood pressure was, however, higher in the patients with proteinuria--mean systolic pressure 161 (SD 18) mm Hg compared with 135 (19) mm Hg (95% confidence interval of difference between means 15 to 38 mm Hg); mean diastolic pressure 90 (SD 12) mm Hg compared with 79 (15) mm Hg (confidence interval 3 to 19 mm Hg). The concentration of serum high density lipoprotein (HDL) cholesterol isolated by precipitation was lower in the patients with proteinuria (confidence interval 0.02 to 0.41 mmol/l). Their concentration of HDL2 cholesterol isolated by ultracentrifugation was also decreased (confidence interval 0.02 to 0.40 mmol/l), whereas HDL3 cholesterol tended to be increased (confidence interval -0.01 to 0.23 mmol/l). There was also a trend for serum cholesterol concentrations to be higher in the presence of proteinuria (confidence interval -0.39 to 1.20 mmol/l). The aggregation of risk factors for atherosclerosis in insulin dependent diabetes mellitus complicated by proteinuria helps to explain the increased prevalence of ischaemic heart disease and peripheral vascular disease reported in these patients. Early renal disease in insulin dependent diabetes may have an important role in hypertension and altered lipoprotein metabolism.