2 in 5 American Adults Will Develop Diabetes

Veronica Hackethal, MD

August 13, 2014

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.

Up to 20% Increase in Diabetes Diagnosis Since the 1980s

The researchers used data from the nationally representative National Health Interview Survey (NHIS) and linked death records in the National Death Index for nearly 600,000 adults from 1985 to 2011. They based diabetes diagnosis on NHIS self-reported data and excluded gestational diabetes. Although researchers did not differentiate between type 1 and type 2 diabetes, they note that overall increases in new diagnoses of diabetes mostly occurred among adults, who usually develop type 2.

Over the 26 years surveyed, results suggest that the incidence of diabetes increased in both women and men. During this time, overall mortality also declined, both for those with and without diabetes.

"The good news is that people are living longer. The number of years lost to diabetes after a person is diagnosed has actually decreased," Dr. Gregg explained. But, he added, "we don't know clearly what the impact of these extra years is going to be on the population overall in the future, so that is a concern." Key issues include rising healthcare costs and quality-of-life burdens related to having such a chronic illness, he said.

From 2000 to 2011, women had a lifetime risk of receiving a diabetes diagnosis of 39.6%, representing a 13% increase from 1985–1989. For the same period, men had a risk of 40.2%, or a 20% increase from 1985–1989.

The future looks even bleaker for some ethnic groups. Hispanic men and women and non-Hispanic black women had the highest lifetime risk — over 50%. Black men had a 45% risk.

Among those diagnosed at age 40, the number of life-years lost to diabetes decreased by about 2 years among both women and men.

The overwhelming increase in diabetes in the general population, however, translated into a 44% increase in cumulative life-years lost to the disease among women and a 46% increase among men. Overall, more years were spent living with diabetes, with a 70% increase in women and a 156% increase in men.

Numbers are "Daunting"; Population Approach Required

"The numbers are daunting," Dr. Gregg admitted, "The main thing that needs to be done to reduce this high lifetime risk is to reduce the rate of new cases. If high-risk people can be identified and given assistance to help change their lifestyles, they can substantially reduce their risk." There are also changes that need to be made across the population, he added.

He and his colleagues note that the profile of increasing incidence and declining mortality has also been observed in the United Kingdom, Canada, and Finland, suggesting that similar dynamics in lifetime risk are taking place in other countries.

In an accompanying comment, Lorraine Lipscombe, MD, an endocrinologist and assistant professor of medicine at Women's College Hospital and the University of Toronto, Ontario, says that recent CDC statistics showing that almost 10% of US adults have diabetes and 1 in 4 do not know it is almost certainly the "tip of the iceberg."

She points out, however, that changing diabetes diagnostic criteria and higher screening rates could have led to earlier detection and diagnosis of diabetes.

Dr. Gregg and colleagues also note this possibility and mention that surveillance data indicate rising rates of diabetes throughout the 1990s, both before and after guideline changes. But they also note that further analyses in their study suggested "increasing detection is not a dominant factor in increased lifetime risk."

"As the number of diabetes cases continues to increase and patients continue to live longer, healthcare systems will increasingly be challenged to meet their needs," Dr. Lipscombe says.

"With close to half of the adult population estimated to develop diabetes during their lifetime," any gains made in diabetes outcomes will soon be overtaken "by the sheer number of people needing care," she stresses.

"Only a population-based approach to prevention can address a problem of this magnitude.

"Prevention strategies should include optimization of urban planning, food-marketing policies, and work and school environments that enable individuals to make healthier lifestyle choices. With an increased focus on interventions aimed at children and their families, there might still be time to change the fate of our future generations by lowering their risk of type 2 diabetes," she concludes.

The authors have reported no relevant financial relationships.

Lancet Diabetes Endocrinol. Published online August 13, 2014. Abstract, Comment

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