Polyunsaturated fats enhance peripheral glucose utilization in rats.

Carbohydrate intolerance is positively correlated with saturated fat consumption. In contrast, individuals consuming diets comprised of polyunsaturated fatty acids (PUFA) have a lower incidence of diabetes mellitus (DM). To test the hypothesis that dietary fats may influence insulin sensitivity, insulin-stimulated glucose utilization was estimated in vivo in rats consuming diets enriched with saturated fatty acids (SFA) (cocoa butter), monounsaturated fatty acid (MUFA) (olive oil), or PUFA derived from corn or fish sources. Each test meal provided (as percentage of calories) 45% carbohydrate, 39% fat, and 16% protein. The meals were consumed over an 8-week period. Metabolic clearance rate (MCR) for glucose was significantly higher (p less than 0.01; 5.69 +/- 0.46 and 5.18 +/- 0.29 ml/kg/min) for diets containing fish and corn oil sources, respectively, when compared to olive oil (4.34 +/- 0.32 ml/kg/min) and cocoa butter (4.61 +/- 0.11 ml/kg/min). Although the MCR between the fish and corn oil diets were not significantly different, the steady state plasma insulin concentration was lower during the fish oil meal (75 +/- 20 microU/ml) when compared to the corn meal (112 +/- 13 microU/ml). Fasting plasma insulin concentrations were significantly lower (p less than 0.01) following the PUFA diets compared to the other two diets. Fasting plasma glucose levels, despite being lower in the fish meal, were insignificantly different among the four test meals. Lastly, body weights were comparable among the four groups tested. These results suggest that diets enriched with PUFA enhance peripheral glucose utilization significantly more than diets comprised of MUFA or SFA sources.(ABSTRACT TRUNCATED AT 250 WORDS)