OBJECTIVE: We investigated whether lifestyle-induced changes in dietary fat quality are related to improvements on glucose metabolism disturbances in Japanese Brazilians at high risk of type 2 diabetes.

METHODS: One hundred forty-eight first- and second-generation subjects with impaired glucose tolerance or impaired fasting glycemia who attended a lifestyle intervention program for 12 mo were studied in the city of Bauru, State of São Paulo, Brazil. Dietary fatty acid intakes at baseline and after 12 mo were estimated using three 24-h recalls. The effect of dietary fat intake on glucose metabolism was investigated by multiple logistic regression models.

RESULTS: At baseline, mean +/- standard deviation age and body mass index were 60+/-11 y and 25.5+/-4.2kg/m(2), respectively. After 12 mo, 92 subjects had normal plasma glucose levels and 56 remained in prediabetic conditions. Using logistic regression models adjusted for age, gender, generation, basal intake of explanatory nutrient, energy intake, physical activity, and waist circumference, the odds ratios (95% confidence intervals) for reversion to normoglycemia were 3.14 (1.22-8.10) in the second tertile of total omega-3 fatty acid, 4.26 (1.34-13.57) in the second tertile of eicosapentaenoic acid, and 2.80 (1.10-7.10) in the second tertile of linolenic acid. Similarly, subjects in the highest tertile of omega-3:omega-6 fatty acid ratio showed a higher chance of improving glucose disturbances (2.51, 1.01-6.37).

CONCLUSIONS: Our findings support the evidence of an independent protective effect of omega-3 fatty acid and of a higher omega-3:omega-6 fatty acid ratio on the glucose metabolism of high-risk individuals.

Key words: omega ration, omega balance, diabetes, impaired glucose tolerance, impaired fasting glycemia, hyperglycemia - Omega-3 Fatty Acids, Eicosapentaenoic Acid, EPA, Linolenic Acid