Undiagnosed diabetes may be less prevalent than first thought

A study from Johns Hopkins Bloomberg School of Public Health found that the overall number of undiagnosed diabetes cases in the U.S. is significantly lower than current government estimates suggest.

Researchers attribute public health efforts to improve diabetes awareness and screening over the last 30 years to better detection of type 2 diabetes in the United States. However, there are some population subgroups that show major disparities in undiagnosed diabetes.

According to the report, undiagnosed diabetes is more prevalent in older and obese adults, racial/ethnic minorities, notably Mexican Americans and Asian Americans, and those without health care access. Individuals who reported an interval of more than one year since their last health care visit also had a high estimated prevalence of confirmed undiagnosed diabetes.

The findings were first published in Diabetes Care. The analysis used government health survey data from 1988-2020, but used the two-test criterion that doctors use when screening for diabetes. The researchers found that about 9.5% of the total diabetes burden in the U.S. is undiagnosed, versus estimates that are in the 20-30% range.

The Centers for Disease Control and Prevention, in its 2020 National Diabetes Statistics Report, estimated that about 2.8% of the 18-and-over population, or roughly seven million Americans, have undiagnosed diabetes. That figure would represent about 22% of the total diabetes burden. The estimates were based on national survey data and using any single blood test result indicating elevated glucose.

The researchers considered individuals in the survey as having “confirmed undiagnosed diabetes” if they had no diabetes diagnosis, yet their test results included elevated results on both a fasting glucose and an HbA1c test. They found that the number of individuals in this category suggested a national prevalence of only 1.23%—less than half the CDC’s most recent estimate based on single test results—and only about 9.5% of the total diabetes prevalence.