Association between insulin and blood pressure in a community population with normal glucose tolerance

The purpose of this study was to examine the relationship between insulin and BP in patients with normal glucose tolerance. The associations between systolic and diastolic BP, age, body mass index, waist/hip ratio, fasting glucose, insulin, fructosamine, glycosylated haemoglobin, lipid profile, and glucose and insulin two hours after 75 g oral glucose were examined in 1,520 employees of a public utility company and non-medical staff of a district hospital. Patients with impaired glucose tolerance or diabetes mellitus (using WHO criteria) were excluded. In men (mean age 35.6 +/- 8.7 years, n = 769), both systolic and diastolic BP were positively associated with age, body mass index, waist/hip ratio, fasting and 2h glucose and insulin, triglycerides and apolipoprotein B, and were negatively associated with glucose/insulin ration, and high density lipoprotein and cholesterol and its subfractions. However, in multivariate analysis only body mass index, age, fasting glucose and insulin were independent predictors of systolic BP, while only body mass index and age predicted diastolic BP. In women, age, glycosylated haemoglobin, 2h glucose/insulin ratio, 2h glucose, fructosamine and triglycerides were predictors of systolic BP. Fasting or 2h insulin, and glucose/insulin ratios did not predict diastolic BP. The results are compatible with the hypothesis that systolic hypertension may reflect a hyper-insulinaemic state even in those with normal glucose tolerance, independent of age and obesity. The association between plasma lipids and blood pressure is probably mediated by insulin and obesity.