Prediabetes - Diabetes

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Prediabetes and diabetes type 2 are common, estimated to affect about 34% and 13% of all U.S. adults in 2018, respectively. Prevalence of diabetes increases with age and was higher among American Indian/Native Alaskan, Hispanic, non-Hispanic Asian, and non-Hispanic Black persons than among non-Hispanic White persons. Diabetes was estimated to be the third leading cause of years lived with disability in 2016 and the seventh leading cause of death in the U.S. in 2017, accounting for more than 80,000 deaths per year. Morbidity (illness) from diabetes is due to macrovascular disease (atherosclerosis), microvascular disease (retinopathy, nephropathy, and neuropathy), and acute complications of hyperglycemia and hypoglycemia. Diabetes was the leading cause of kidney failure, lower-limb amputations, and new cases of blindness among U.S. adults.

Risk factors associated with the development of diabetes in adults include older age, family history, overweight and obesity, dietary and lifestyle factors, environmental exposure, and others. Three tests can be used to identify diabetes and prediabetes: hemoglobin A1c (HbA1c), fasting plasma glucose level, or oral glucose tolerance test. The American Diabetes Association (ADA) has set criteria for the diagnosis of both diabetes and prediabetes. For diabetes, the criteria are a HbA1c greater than or equal to 6.5%, fasting plasma glucose greater than or equal to 126, or oral glucose tolerance test glucose levels of greater than or equal to 200. For prediabetes, the criteria are HbA1c 5.7% to 6.4%, fasting plasma glucose between 100 and 125, and glucose tolerance test glucose levels between 140 and 199.

In 2015, the U.S. Preventive Services Task Force (USPSTF) recommended screening for abnormal blood glucose levels as part of cardiovascular risk assessment in adults aged 40 to 70 years who were overweight or obese. In addition, it recommended that clinicians offer or refer patients with abnormal blood glucose levels to intensive behavioral counseling sessions to promote a healthful diet and physical activity. This year, the USPSTF updated that recommendation to include all non-pregnant adults aged 35 to 70 years who are overweight or obese and who do not have symptoms of diabetes. While prediabetes is usually asymptomatic, symptoms of diabetes may include excessive thirst, frequent urination, unexplained weight loss, blurred vision, and tiredness.

The goal of screening for prediabetes and diabetes is to identify and treat these conditions earlier rather than later to prevent progression of disease and adverse outcomes including heart attacks, kidney disease, impaired vision, and death. While there is little evidence that screening for prediabetes and diabetes by itself improves health outcomes, there is good direct evidence that interventions for newly diagnosed diabetes can have a positive effect on all-cause mortality, diabetes-related mortality, and the risk of heart attack after 10 to 20 years of intervention. In addition, there is good evidence that lifestyle interventions such as proper diet and exercise in those with prediabetes can reduce progression to type 2 diabetes.

So, if you or someone you know is overweight or obese, not pregnant, and between the ages of 35 to 70 years, it is important to get screened for prediabetes and diabetes, especially if you have any relatives who have type 2 diabetes. Also, even if the screening is negative, it is important to repeat the screening at regular intervals, for example annually.

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 By Peter Galvin, MD

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