About 40% of US adults will develop diabetes, primarily type 2, in their lifetime, and over 50% of some ethnic minorities will be affected, according to new research from the Centers for Disease Control and Prevention (CDC) and Emory University, Atlanta, Georgia, published online August 13 in Lancet Diabetes & Endocrinology.

This is substantially higher than previous estimates that were based on incidence and mortality from the 1990s, say the researchers.

"We have found that over the past few decades the chance that the average person will develop diabetes at some point in their lifetime has increased tremendously," commented lead author Edward Gregg, PhD, chief of the epidemiology and statistics branch of the division of diabetes translation at the CDC.

Many factors could explain the striking increase in diabetes over the past 3 decades, says Dr Gregg, but the central reason is obesity. "And people are living longer, so they basically have more years of life in which to develop diabetes," he observed.

"Obesity really has been the driving force," he noted. "There is some encouraging evidence that obesity trends might be flattening, and we hope that will have an effect on diabetes, which follows very closely what happens in obesity. But it's not clear yet whether we're seeing that happen."

Other contributory factors include dietary changes, such as eating in restaurants more often, larger portion sizes, fast food, sugary beverages, refined sugars and carbohydrates, and fewer whole grains. Declining physical-activity levels play an independent role, he added.