After years of rapid increase, a new study published in JAMA reveals the prevalence of type 2 diabetes in the US has leveled off, offering some hope that measures to combat this disease are beginning to take effect. However, the study also found that diabetes and prediabetes continue to affect almost half of adults in the country.

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While diabetes and prediabetes affects almost half the US population, researchers say prevalence of the condition is leveling off.

The figures on US prevalence and trends in diagnosed and undiagnosed diabetes were estimated by Andy Menke, PhD, an epidemiologist at Social & Scientific Systems Inc. in Silver Spring, MD, and colleagues.

The team used National Health and Nutritional Examination Survey (NHANES) data involving 23,634 adults from 1988-2010 to estimate diabetes trends, with a further 2,781 from 2011-12 to estimate the recent prevalence of the condition.

The data reveals that in 2011-12, around 12-14% of the US adult population had diabetes, while prediabetes affected approximately 37-38% of the population.

The cost of diabetes to the US is enormous, increasing by 41% between 2007 and 2012, from $174 billion to $245 billion, according to the study authors. The largest part of the cost is hospital inpatient care, which accounts for 43%, followed by prescription medications to treat complications caused by diabetes, accounting for 18% of diabetes costs.

In their study, Menke and colleagues used a previous diagnosis of diabetes among participants to define the prevalence of diabetes in the US.

Where diabetes had not been previously diagnosed, the team identified the condition via the presence of a hemoglobin A1c level at 6.5% or greater or a fasting plasma glucose (FPG) level of 126 mg/dL or greater. Alternatively, diabetes was identified via a 2-hour plasma glucose (2-hour PG) level of 200 mg/dL or greater.

Study findings 'offer hope'

The study findings revealed that the unadjusted prevalence for total diabetes among the US population was 14.3% between 2011 and 2012. The prevalence of diagnosed diabetes was 9.1%, standing at 5.2% for undiagnosed diabetes and 38% for prediabetes. Among those with diabetes, 36.4% were undiagnosed.

Fast facts about diabetes
  • Diabetes is a lifelong condition characterized by raised glucose levels
  • 29.1 million Americans have diabetes
  • 86 million Americans have prediabetes.

Learn more about diabetes

Assessing the prevalence of diabetes among different ethnic groups, the team found it was highest among non-Hispanic black study participants (21.8%) and non-Hispanic Asian participants (22.6%), compared with non-Hispanic white participants (11.3%).

In all sex and racial/ethnic categories, it was found that prediabetes prevalence was greater than 30%. This was highest among two groups: non-Hispanic white study participants and non-Hispanic black participants.

In both sexes, all age groups, in every racial/ethnic group and by all education levels, diabetes prevalence rates increased from 9.8% in 1988-1994 to 12.4% in 2011-2012.

The good news this study reports is that while the prevalence of diabetes was seen to increase during the study periods 1988-1994 and 2011-2012, prevalence levels for the study periods 2007-2008 and 2011-2012 saw little change. This suggests, according to the study authors, that there has been an important leveling off in diabetes prevalence in the US.

"This plateauing of diabetes prevalence is consistent with obesity trends in the United States showing a leveling off around the same period," note the study authors.

"These figures offer hope," say Dr. William Herman and Dr. Amy Rotheberg - both of the University of Michigan Health System in Ann Arbor, MI - in an editorial linked to the study.

Dr. Herman and Dr. Rotherberg point to three influencing factors on this trend: a cultural shift in attitudes to diabetes, the American Medical Association (AMA) recognizing obesity as a disease, and an increasing focus on addressing food policy and even the spaces and places where we live and work - referred to collectively as "the built environment."

Thanks to the AMA and Centers for Disease Control and Prevention (CDC), the study says, people at risk of diabetes are being identified earlier.

Dr. Herman and Dr. Rothberg note:

"Providing insurance coverage for intensive behavioral therapies for obesity and using behavioral economic approaches to encourage their uptake are further removing barriers to patient engagement and are providing strong incentives for individual behavioral change.

Together, these multifaceted approaches are addressing both environmental factors and individual behaviors appear to be slowing the increase in obesity and diabetes and facilitating the diagnosis and management of diabetes. Progress has been made, but expanded and sustained efforts will be required."

Last year, Medical News Today reported that the rise in the prevalence of diabetes in the US was considered "alarming" by the CDC.

Written by Jonathan Vernon