In study A, explain why the researchers adjusted “BMI and initial and changes in diet and lifestyle covariates” when analyzing the association between sugary beverage intake and diabetes risk?   Objective: We evaluated the associations of long-term changes in consumption of sugary beverages (including sugar-sweetened beverages and 100% fruit juices) and artificially sweetened beverages (ASBs) with subsequent risk of type 2 diabetes.   Research design and methods: We followed up 76,531 women in the Nurses' Health Study (1986-2012), 81,597 women in the Nurses' Health Study II (1991-2013), and 34,224 men in the Health Professionals' Follow-up Study (1986-2012). Changes in beverage consumption (in 8-ounce servings/day) were calculated from food frequency questionnaires administered every 4 years.   Results: During 2,783,210 person-years of follow-up, we documented 11,906 incident cases of type 2 diabetes. After adjustment for BMI and initial and changes in diet and lifestyle covariates, increasing total sugary beverage intake (including both sugar-sweetened beverages and 100% fruit juices) by >0.50 serving/day over a 4-year period was associated with a 16% (95% CI 1%, 34%) higher diabetes risk in the subsequent 4 years. Increasing ASB consumption by >0.50 serving/day was associated with 18% (2%, 36%) higher diabetes risk. Replacing one daily serving of sugary beverage with water, coffee, or tea, but not ASB, was associated with a 2-10% lower diabetes risk.   Conclusions: Increasing consumption of sugary beverages or ASBs was associated with a higher risk of type 2 diabetes, albeit the latter association may be affected by reverse causation and surveillance bias.

In study A, explain why the researchers adjusted “BMI and initial and changes in diet and lifestyle covariates” when analyzing the association between sugary beverage intake and diabetes risk?

Objective: We evaluated the associations of long-term changes in consumption of sugary beverages (including sugar-sweetened beverages and 100% fruit juices) and artificially sweetened beverages (ASBs) with subsequent risk of type 2 diabetes.

Research design and methods: We followed up 76,531 women in the Nurses' Health Study (1986-2012), 81,597 women in the Nurses' Health Study II (1991-2013), and 34,224 men in the Health Professionals' Follow-up Study (1986-2012). Changes in beverage consumption (in 8-ounce servings/day) were calculated from food frequency questionnaires administered every 4 years.

Results: During 2,783,210 person-years of follow-up, we documented 11,906 incident cases of type 2 diabetes. After adjustment for BMI and initial and changes in diet and lifestyle covariates, increasing total sugary beverage intake (including both sugar-sweetened beverages and 100% fruit juices) by >0.50 serving/day over a 4-year period was associated with a 16% (95% CI 1%, 34%) higher diabetes risk in the subsequent 4 years. Increasing ASB consumption by >0.50 serving/day was associated with 18% (2%, 36%) higher diabetes risk. Replacing one daily serving of sugary beverage with water, coffee, or tea, but not ASB, was associated with a 2-10% lower diabetes risk.

Conclusions: Increasing consumption of sugary beverages or ASBs was associated with a higher risk of type 2 diabetes, albeit the latter association may be affected by reverse causation and surveillance bias.