Association of the fatty acid profile of serum lipids with glucose and insulin metabolism during 2 fat-modified diets in subjects with impaired glucose tolerance.

BACKGROUND Both the amount and quality of dietary fat can modify glucose and insulin metabolism. OBJECTIVE The objective was to examine the relation between serum lipid fatty acids and glucose metabolism before and after the consumption of a diet enriched in either monounsaturated (Mono diet) or polyunsaturated (Poly diet) fatty acids. DESIGN After consuming a high-saturated-fat run-in diet for 3 wk, 31 subjects with impaired glucose tolerance were randomly counseled to consume the Mono [40% fat; 11%, 19%, and 8% of energy as saturated, monounsaturated, and polyunsaturated fatty acids (S:M:P), respectively] or the Poly (34% fat; S:M:P of 11%:10%:10%) diet for 8 wk. Serum lipid fatty acids were measured, and an intravenous-glucose-tolerance test was performed at baseline and at 8 wk. RESULTS At baseline, a higher glucose effectiveness (S(G)) was associated with higher proportions of oleic (r = 0.57, P = 0.04) and alpha-linolenic (r = 0.64, P = 0.01) acids in phospholipids. An increase in the proportions of oleic and alpha-linolenic acids in phospholipids was associated with a decrease in fasting plasma glucose [r = -0.53 (P = 0.002) and r = -0.47 (P = 0.009), respectively]. An increase in the S(G) was associated with an increase in the proportion of oleic acid (r = 0.55, P = 0.004) and with a decrease in that of arachidonic acid (r = -0.40, P = 0.04) in phospholipids. CONCLUSIONS The beneficial changes in fasting plasma glucose and in the S(G) during the Mono diet were associated with alterations in the proportions of oleic, alpha-linolenic, and arachidonic acids in phospholipids.