Elevated fasting plasma insulin in a general aged population: An innocent companion of cardiovascular diseases

OBJECTIVE: Although high insulin levels have been linked to cardiovascular disease, the role of insulin as an independent risk factor has been questioned. Our objective was to examine the association of fasting plasma insulin with cardiovascular disease as well as to investigate the prognostic value of insulin with respect to survival. DESIGN: A 5-year follow-up of random samples from four birth cohorts aged 65 (n = 660), 75 (n = 194), 80 (n = 179), and 85 (n = 162) years at baseline. SETTING: Two urban communities in southern Finland. MEASUREMENTS: Clinical and laboratory investigation at base line with collection of date and cause of death information during follow-up. RESULTS: Subjects with cardiovascular disease generally had higher levels of fasting plasma insulin than did subjects without cardiovascular disease (13.9 mU/L vs 11.2 mU/L, P < .001). Heart failure and hypertension were associated with significant 30 to 80% elevations of insulin levels in all but the oldest group. In the 65-year-old group, all vascular diseases were associated with significantly elevated insulin. The associations were generally not explained by body mass index or by use of diuretics or beta-blockers. During the follow-up, insulin was generally not associated with an impaired survival. On the contrary, in subjects with manifest cardiovascular disease, high insulin was associated with a rather favorable 5-year survival prognosis. Exclusion of subjects who died during the first 500 days of follow-up did not change these associations. CONCLUSION: Albeit fasting plasma insulin appeared to be secondarily associated with cardiovascular disease in this general aged population, it was related to a fair or favorable survival prognosis.