Dietary Fat and Incidence of Type 2 Diabetes in Older Iowa Women

Abstract

OBJECTIVE -To examine the associations between reported intakes of dietary fat and incident type 2 diabetes.RESEARCH DESIGN AND METHODS -We studied the relation between dietary fatty acids and diabetes in a prospective cohort study of 35,988 older women who initially did not have diabetes. Diet was assessed with a food frequency questionnaire at baseline, and 1,890 incident cases of diabetes occurred during 11 years of follow-up. RESULTS -After adjusting for age, smoking, alcohol consumption, BMI, waist-to-hip ratio, physical activity, demographic factors, and dietary magnesium and cereal fiber, diabetes incidence was negatively associated with dietary polyunsaturated fatty acids, vegetable fat, and trans fatty acids and positively associated with -3 fatty acids, cholesterol, and the Keys score. After simultaneous adjustment for other dietary fat, only vegetable fat remained clearly related to diabetes risk. Relative risks across quintiles of vegetable fat intake were 1.00, 0.90, 0.87, 0.84, and 0.82 (P ϭ 0.02). Diabetes risk was also inversely related to substituting polyunsaturated fatty acids for saturated fatty acids and positively correlated to the Keys dietary score.CONCLUSIONS -These data support an inverse relation between incident type 2 diabetes and vegetable fat and substituting polyunsaturated fatty acids for saturated fatty acids and cholesterol. Diabetes Care 24:1528 -1535, 2001A lthough a low-fat diet is recommended for diabetic and nondiabetic patients (1), findings from epidemiological studies on the association of total dietary fat with type 2 diabetes or insulin sensitivity have been inconsistent (2-8). Metabolic and epidemiological studies suggest that dietary fat subtypes may be relevant to diabetes pathophysiology. Specific dietary fatty acids may influence the development of diabetes by modifying the phospholipid composition of cell membranes, which in turn may alter the function of the insulin receptor (9,10).While women who returned the baseline questionnaire. Respondents had a lower mean BMI (0.4 kg/m 2 less), were 3 months older, and were more likely to live in counties that were rural and less affluent than nonrespondents (11).Women were excluded from analysis if they reported implausibly high (Ͼ5,000 kcal) or low (Ͻ600 kcal) energy intakes, left Ն30 items blank on the foodfrequency questionnaire, or had diabetes at baseline. Women were considered to have diabetes at baseline if they responded "yes" or "don't know" to one of the following questions: 1) have you ever been told by a doctor that you have sugar diabetes? and 2) have you ever taken insulin or pills for sugar diabetes (or to lower blood glucose)? After exclusions, 35,988 women remained eligible for the study. Data collectionThe baseline questionnaire included questions on known or suspected risk factors for diabetes, such as age, BMI, waistto-hip ratio (WHR), physical activity, alcohol consumption, and smoking history. BMI was calculated from weight and height measurements provided by the participants. WHR was calculated as...

Food consumption and the incidence of type II diabetes mellitus

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