THE RELATIONSHIP OF FASTING INSULIN LEVELS TO VASCULAR RISK-FACTORS IN A GENERAL-PRACTICE IN NORTHERN-IRELAND

Objective, To investigate the relationship between insulin and vascular risk factors in a healthy male population at high risk of ischaemic heart disease. Design. Computer-generated random number selection of subjects. Setting. A suburban general practice population (total practice population 4500) in Northern Ireland. Subjects. Four hundred male subjects, aged 35-65 years, were randomly selected with 273 responding. Intervention. At interview, each subject completed a questionnaire, had blood pressure measured and a 12-lead ECG recorded. The next morning, fasting blood samples were taken and a timed overnight urine collection for the albumin excretion rate was returned. Results. To exclude the confounding effects of other variables on insulin concentrations, a healthy nonobese, nondiabetic, normotensive group with no history of ischaemic heart disease, no family history of diabetes and not taking drugs was identified (n = 120). Within this group there was a significant correlation between insulin and triglyceride (r = 0.30; P < 0.05), high-density lipoprotein (HDL) cholesterol (r = 0.24; P < 0.05) and glucose (r = 0.30; P < 0.05). A group with higher insulin levels (n = 22) were compared to a group with lower insulin levels (n = 22). Serum triglyceride was higher (1.29 +/- 0.1 vs. 1.00 +/- 0.08 mmol L(-1); P < 0.05), HDL cholesterol was lower (1.26 +/- 0.06 vs. 1.50 +/- 0.09 mmol L(-1); P < 0.05) and plasma glucose higher (5.2 +/- 0.1 vs. 4.9 +/- 0.1 mmol L(-1); P < 0.05) in the group with higher insulin levels. Conclusions. There is a relationship between insulin and triglyceride, HDL cholesterol and glucose but not blood pressure, cholesterol or low-density-lipoprotein (LDL) cholesterol in a healthy population at high risk of ischaemic heart disease.