Introduction: The beneficial effects of the overall Mediterranean dietary pattern on cardiovascular risk factors and on carbohydrate metabolism are well known; however, it is unclear whether the consumption of olive oil in particular is able to reduce the incidence of type 2 diabetes.
Objective: To evaluate the specific effect of olive oil consumption on the risk of developing type 2 diabetes mellitus in a large Spanish cohort (the SUN Project).
Methods: We followed up 10,491 participants for a median of 5.7 years. Habitual diet was assessed at baseline with a semi-quantitative 136-item food-frequency questionnaire previously validated in Spain. The outcome of interest was incident type 2 diabetes diagnosed by a physician and confirmed by review of a medical report. The multivariate-adjusted odds ratios for incident type 2 diabetes for each of the 4 upper quintiles of olive oil consumption using the lowest quintile as the reference were assessed using logistic regression models.
Results: At baseline mean age was 38.9 + 11.38 year with a BMI of 23.8 + 3.41 kg/m². Forty two new cases of diabetes mellitus were diagnosed during follow-up. The adjusted odds ratio for the highest vs. the lowest quintile of consumption of olive oil was 1.11 (95% CI: 0.45-2.78; p for trend = 0.32).
Conclusions: We found no association between olive oil consumption and the incidence of type 2 diabetes. The lack of association could be attributed to the small number of observed incident cases of diabetes. Further studies in Mediterranean countries with a longer follow-up and a higher baseline risk are needed to evaluate this association.