Insulin resistance and beta-cell dysfunction in adults with different patterns of diet: a cross-sectional study in north-western Tanzania.

Background: The diabetes burden in sub-Saharan Africa is rising, but there is little African data on associations between diet, insulin resistance, and beta-cell dysfunction.

Objective: We investigated the association between dietary patterns and insulin resistance and beta-cell dysfunction among adults in Mwanza, Tanzania.

Methods: In a cross-sectional study involving adults with or without HIV, insulin resistance and beta-cell dysfunction were calculated from plasma insulin and glucose measures during an oral glucose tolerance test. Diet data were collected using a validated food frequency questionnaire and dietary patterns were derived by principal component analysis and reduced rank regression. Logistic regression analysis was used to assess the association between exposure variables (dietary patterns terciles) with outcome variables (insulin resistance and beta-cell dysfunction), adjusting for HIV status, age, sex, body mass index, alcohol consumption, and smoking.

Results: Of 462 participants, the mean age was 42 (±12) years, 58% were females, and 60% were HIV-infected. Carbohydrate-dense patterns were associated with more insulin resistance by HOMA-IR (aOR 2.7, 95% CI 1.5; 4.8) and Matsuda index (aOR 3.7, 95% CI 2.0; 6.7), but not with either HOMA-β, insulinogenic index or oral disposition index. The level of adherence to either the vegetable-rich or vegetable-poor pattern was not associated with any of the markers of insulin resistance or beta-cell dysfunction. HIV infection did not affect the association between patterns of diet and glucose metabolism outcomes.

Conclusion: The lack of association between either vegetable-rich or vegetable-poor patterns with insulin resistance or beta cell dysfunction requires further research.