HIGH PLASMA-INSULIN IS ASSOCIATED WITH LOWER LDL CHOLESTEROL IN ELDERLY INDIVIDUALS

To investigate possible relationships between plasma low density lipop rotein (LDL) cholesterol and fasting plasma insulin in the elderly, cr oss-sectional random samples of age cohorts (65, 75, 80 and 85 years, n = 1188, M/F 38/62%) were studied in the neighbouring cities of Helsi nki and Vantaa, Finland. Plasma total and high density lipoprotein (HD L) cholesterol, plasma triglycerides, blood glucose and plasma insulin were measured after an overnight fast. LDL cholesterol was calculated using the Friedewald equation. Statistical analyses were performed se parately in subjects with non-insulin-dependent diabetes mellitus (NID DM, n = 219) and non-diabetic subjects (n = 969). Comparison of lipid levels by insulin quartile (I < 7.4 IU/l, II 7.4-10.0, III 10.1-15.0, IV > 15.0) showed that total and LDL cholesterol decreased in the high est insulin quartile (P = 0.003). This trend prevailed after adjustmen ts for age, gender, body mass index, blood glucose and serum triglycer ides,.and it was significant also in normotriglyceridemic (serum trigl ycerides < 2.3 mmol/l) subjects. Furthermore, the association between high insulin and lower cholesterol was seen in normoglycemic (fasting blood glucose < 6.7 mmol/l) and diabetic subjects. Lower LDL cholester ol in elderly subjects with higher fasting insulin may reflect poor he alth or a 'harvesting' effect, but the results may also be due to effe cts of insulin on LDL catabolism and/or cholesterol absorption.