Diet soda and sugar-sweetened soda consumption in relation to incident diabetes in the Northern Manhattan Study

Background: Artificially (diet) and sugar-sweetened (regular) soda consumption have been associated with an increased risk of diabetes, but the literature on diet soda is inconsistent and the mechanisms unclear. Objective: We examined the relation between diet soda and regular soda consumption with the risk of incident diabetes in a longitudinal multiethnic population-based cohort. Methods: The study population included 2019 participants (mean ± SD age: 69 ± 10 y; 64% women; 23% white, 22% black, 53% Hispanic) in the Northern Manhattan Study who were free of diabetes and stroke at baseline. Soda consumption was assessed by a food-frequency questionnaire at baseline and examined continuously and categorically ( < 1/mo: sugar-sweetened = 908, diet = 1615; 1/mo-6/wk: sugar-sweetened = 830, diet = 298; daily: sugar-sweetened = 281, diet = 106). Weibull regression models were used to estimate the associations between soda consumption and incident diabetes, adjusting for demographics and vascular risk factors including body mass index (BMI) and calorie consumption. Results: During a mean ± SD follow-up of 11 ± 5 y, 368 participants developed diabetes. Sugar-sweetened soda was positively associated with incident diabetes (per soda per day HR = 1.15, 95% CI: 1.02, 1.31). The observed association between diet soda and elevated risk of diabetes was largely explained by BMI at the time of diet assessment, though the association remained strong and independent of BMI among those who were overweight or obese (daily compared to < 1/mo: HR = 1.63, 95% CI: 1.04, 2.55). Conclusions: This study supports the importance of sugar-sweetened beverage consumption in the diabetes epidemic. However, the results support previous studies suggesting that switching to artificially sweetened diet beverages may not lower the risk of diabetes, as diet soda consumption cannot be ruled out as an independent diabetes risk factor.