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.