Impact of dietary fat composition on prediabetes: a 12-year follow-up study.

OBJECTIVE: Dietary fatty acid composition likely affects prediabetic conditions such as isolated impaired fasting glucose (IFG) or impaired glucose tolerance (IGT); however, this risk has not been evaluated in a large population nor has it been followed prospectively.

DESIGN: Diet, physical activity, anthropometric, socio-economic and blood glucose data from the Atherosclerosis Risk in Communities (ARIC) study were obtained from BioLINCC. Cox proportional hazards regression models were used to evaluate associations of dietary SFA, MUFA, PUFA, n-3 fatty acid (FA) and n-6 FA intakes with incidence of one (isolated IFG) or two (IFG with IGT) prediabetic conditions at the end of 12-year follow-up.

SETTING: Study volunteers were from counties in North Carolina, Mississippi, Minnesota and Maryland, USA.

SUBJECTS: Data from 5288 volunteers who participated in the ARIC study were used for all analyses reported herein.

RESULTS: The study population was 62% male and 84 % white, mean age 53·5 (sd 5·7) years and mean BMI 26·2 (sd 4·6) kg/m2. A moderately high intake of dietary MUFA (10-15 % of total daily energy) was associated with a 10 % reduced risk of isolated IFG incidence, while a high intake of n-3 FA (>0·15 % of total daily energy) was associated with a 10 % increase in risk. Curiously, moderately high intake of n-6 PUFA (4-5 % of total daily energy) was associated with a 12 % reduction in IFG and IGT incidence.

CONCLUSIONS: MUFA, n-3 and n-6 FA contribute differently to the development of isolated IFG v. IFG with IGT; and their mechanism may be more complex than originally proposed.