Improvement in overall diet quality helps lower the risk of type 2 diabetes mellitus (DM), independent of adopting other healthful behaviors, including increased physical activity and body weight loss, according to the results of a new study.
In an analysis of 3 large cohort studies of men and women conducted by researchers at the Harvard School of Public Health, Boston, the risk of type 2 DM was reduced by about 20% in those who improved their diet quality index scores by 10% over 4 years compared with those who made no changes to their diets.
“We found that diet was indeed associated with diabetes independent of weight loss and increased physical activity,” said lead author Sylvia Ley, PhD, RD, a postdoctoral fellow at the Harvard School of Public Health, at the American Diabetes Association (ADA) 74th Scientific Sessions. “If you improve other lifestyle factors, you reduce your risk for type 2 diabetes even more, but improving diet quality alone has significant benefits.”
Dr Ley noted that it is often difficult for people to maintain a calorie-restricted diet for a long time. “We want them to know that if they can improve the overall quality of what they eat—consume less red meat and sugar-sweetened beverages and more fruits, vegetables and whole grains—they are going to improve their health and reduce their risk for diabetes,” she said.
Lifestyle changes, including individually tailored, macronutrient composition–focused, calorie-restricted interventions, can prevent or delay type 2 DM among those at high risk, according to randomized controlled trials. However, it is unclear whether improving overall diet quality by itself is associated with reduced risk of DM among healthy adults.
Dr Ley and colleagues investigated the association between diet quality changes during a 4-year period and subsequent 4-year type 2 DM risk as well as simultaneous changes in multiple lifestyle factors on that risk (Abstract 74-OR).
The investigators prospectively followed more than 148,000 participants without DM at baseline in the Nurses’ Health Study (1986-2006), Nurses’ Health Study II (1991-2011), and Health Professionals Follow-up Study (1986-2010). They used the Alternative Healthy Eating Index score to assess diet quality. Associations between changes in diet quality, physical activity, and body weight and DM risk were evaluated simultaneously.
The researchers documented more than 9000 incident cases of type 2 DM during the more than 2.3 million person-year follow-up.
A greater than 10% decrease in diet quality scores over 4 years was associated with higher subsequent DM risk with multiple adjustments, and at least 10% improvement in dietary scores was associated with lower risk, Dr Ley said during her presentation at the ADA meeting. When simultaneous relationships among 4-year changes in diet quality, physical activity, and body weight were assessed, improvement in each behavioral factor was independently associated with lower incident DM.
"Regardless of where participants started, improving diet quality was beneficial for all," Dr Ley noted.