SAN FRANCISCO – Even small improvements to the quality of diet can help stave off diabetes.
More specifically, adults whose diet quality scores improved by at least 10% were 9% less likely to develop type 2 diabetes in the next 4 years, and those whose diet quality scores worsened by at least 10% were 18% more likely to develop diabetes, according to an analysis of data from three longitudinal observational studies involving 184,417 people.
Sylvia H. Ley, Ph.D.
Those changes in diabetes risk were statistically significant, Sylvia H. Ley, Ph.D., reported at the annual scientific sessions of the American Diabetes Association.
They analyzed data on participants in the Nurses Health Study I, Nurses Health Study II, and the Health Professionals Follow-Up Study who were followed for at least 20 years in each study and asked every 2 years about incident diabetes and every 4 years about the contents of their diet, among other topics. Dr. Ley and her associates used the Alternative Healthy Eating Index to assess diet quality.
Nearly 10,000 new cases of type 2 diabetes were reported during more than 2 million person-years of follow-up, Dr. Ley of Harvard University’s School of Public Health, Boston, said in a press briefing.
The associations between dietary changes and diabetes risk affected all people, whether they ate well or poorly, according to subset analyses of participants grouped as those having the poorest quality diet, medium quality, or highest quality diet. "Regardless of where you start, improving your diet quality is helpful in diabetes prevention," Dr. Ley said.
The reduced diabetes risk from improving diet quality was independent of effects from physical activity or reduced body weight, she said.
The Alternative Healthy Eating Index focused on intake of 11 components: red meat, nuts, sugar-sweetened beverages, fruits, vegetables, polyunsaturated fat, trans fat, omega fats, alcohol, sodium, and whole grains, with up to 10 points for intake of each. A perfect diet score was 110, so a mere 11-point gain provided a 10% improvement in diet quality, she said.
A 10% improvement in diet quality is "not that difficult" to make, Dr. Ley said. Nearly everyone in the study started with a poor-quality diet, and many made more than a 10% improvement in diet quality scores.
The bottom line is that changing one’s diet can be helpful, she said. "I think healthy eating is somewhat abstract, and that people still have difficulty understanding what that means," Dr. Ley said. "I think it’s helpful to provide more information on what is healthy and what is better quality eating."
A separate study by Dr. Ley and her associates found that the quality of foods and drinks consumed is more important than the quantity and that a number of different dietary strategies can reduce diabetes risk (including a Mediterranean diet, vegetarian diet, low-glycemic-index diet, or moderately low carbohydrate diet) because they are rich in whole grains, fruits, vegetables, legumes, and nuts, with moderate to low amounts of alcohol, refined grains, red or processed meats, and sugar-sweetened beverages (Lancet 2014;383:1999-2007).
Other previous randomized, controlled studies had shown that restricting dietary calories can help protect against development of diabetes, but that dietary strategy is difficult for people to maintain, Dr. Ley said. "That has led us to take more food-based approaches," she said. In addition, those studies predominantly looked at people who were at high risk for diabetes, whereas the current study looked at a normal healthy population.
The current findings can’t be generalized to the entire population without further study, however, because participants in the three studies in the analysis were relatively well-educated health care professionals and 98% were white.
Dr. Ley reported having no financial disclosures.
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