High-fat diets are associated with
insulin resistance, however, this effect may vary depending on the type of fat consumed. The purpose of this study was to determine the relationship between intakes of specific dietary
fatty acids (assessed by 3-day diet records and
fatty acid composition of serum
cholesterol esters [CEs] and
phospholipids [PLs]) and
glucose and
insulin concentrations during an oral
glucose tolerance test (OGTT). Nineteen men and 19 women completed the study. Nine subjects had
type 2 diabetes or
impaired glucose tolerance. Fasting
insulin correlated with reported intakes of total fat (r = .50, P < .01), monounsaturated fat (r = .44, P < .01), and saturated fat (r = .49, P < .01), but not with
trans fatty acid intake (r = .11, not significant [NS]). Fasting
glucose also correlated with total (r = .39, P < .05) and monounsaturated fat intakes (r = .37, P < .05). In multivariate analysis, both total and saturated fat intake were strong single predictors of fasting
insulin (R2 approximately .25), and a model combining dietary and anthropometric measures accounted for 47% of the variance in fasting
insulin. Significant relationships were observed between fasting
insulin and the serum CE enrichments of myristic (C14:0), palmitoleic (C16:1), and dihomo-gamma-linolenic (C20:3n-6)
acids. In multivariate analysis, a model containing CE 14:0 and percent body fat explained 45% of the variance in fasting
insulin, and C14:0 and age explained 30% of the variance in fasting
glucose. PL C20:3n-6 explained 30% of the variance in fasting
insulin, and a model including PL C18:1n-11 cis, C20:3n-6, age and body fat had an R2 of .58. In conclusion, self-reported intake of saturated and monounsaturated
fats, but not
trans fatty acids, are associated with markers of
insulin resistance. Furthermore, enhancement of dihomo-gamma-linolenic and
myristic acids in serum CE and PL, presumably markers for dietary intake, predicted
insulin resistance.