Despite Advances, Rates of Glycemic Control Backsliding in Past Decade

Elizabeth Selvin, PhD

Despite practice-changing advances in technology and pharmacy, new research from the Johns Hopkins Bloomberg School of Public Health suggests rates of glycemic control among patients with diabetes have declined significantly in the past decade.

Using data from the National Health and Nutrition Examination Survey (NHANES), investigators paint a picture portraying more than a decade of progress lasting from 1999 to the early 2010s that has been derailed and is currently backsliding.

"These trends are a wake-up call, since they mean that millions of Americans with diabetes are at higher risk for major complications," said lead investigator Michael Fang, PhD, a postdoctoral fellow at the Bloomberg School, in a statement. "Our study suggests that worsening control of diabetes may already be having a detrimental effect at the national level."

The current landscape of diabetes management is one of the most complex in all of medicine. A paradigm where historic progress has been disrupted by rising rates of obesity and inactivity, Fang and a team of colleagues sought to identify and provide an overview of trends in diabetes treatment and risk-factor control from 1999-2018.

To do so, the current study was designed as a cross-sectional analysis of all patients enrolled in NHANES from 199-2018 who were 20 years of age or older with a diagnosis of diabetes and who were not pregnant. For the purpose analysis, surrey years were pooled into 4-year intervals—defined as 1999-2002, 2003-2006, 2007-2010, 2011-2014, and 2015-2018.

Specific risk factors of interest for the analysis included HbA1c, blood pressure, and lipids. Glycemic control was defined as an HbA1c less than 7.0%, blood pressure control was defined as less than 140/90 mmHg but investigators also considered a more stringent target of 130/80 mmHg, and lipid control was defined as non-HDL-C target was less than 130 mg/dL.

Initial analyses indicated trends for glycemic, blood pressure, and lipid control were nonlinear with an apparent inflection point around 2010. Between 1999-2002 and 2007-2010, the proportion of patients achieving glycemic control increased from 44.0% (95% CI, 38.9-49.3) to 57.4% (95% CI, 52.9-61.8). However, investigators noted this number began to decline and fell to 50.5% in 2015-2018 (95% CI, 45.8-55.3).

For blood pressure control, rates rose of patients with diabetes reaching a goal of less than 140/90 mmHg rose from 64.0% in 1999-2002 (95% CI, 59.2-68.5) to 74.2% in 2011-2014 (95% CI, 70.7-77.4). Similar to trends in glycemic control, this number decline to 70.4% in 2015-2018 (95% CI, 66.7-73.8). Investigators noted similar trends were observed when using a blood pressure target of less than 130/80 mmHg. For lipid control, the proportion of patients with a non-HDL-C level of less than 130 mg/dL increased from 25.3% in 1999-2002 (95% CI, 20.8-30.4) to 52.3% in 2007-2010 (95% CI, 49.2-55.3). However, this improvement appeared to plateau with a rate of 55.7% in 2015-2018 (95% CI, 50.8-60.5).

In analyses assessing percentage of patients achieving glycemic, blood pressure, and lipid control goals, results indicated rates more than doubled from 9.0% in 1999-2002 to 24.9% in 2007-2010 then became stagnant with a rate of 22.2% from 2015-2018 (95% CI, 17.9-27.3). Investigators highlighted the annual rate of change in diabetes control decreased for all outcomes when all years were modeled.

"These are concerning findings. There has been a real decline in glycemic control from a decade ago, and overall, only a small proportion of people with diabetes are simultaneously meeting the key goals of glycemic control, blood pressure control, and control of high cholesterol," said senior investigator Elizabeth Selvin, PhD, MPH, a professor in the Bloomberg School's Department of Epidemiology.

When assessing trends in medication use, investigators found the percentage of patients who used any glucose-lowering medication or blood pressure-lowering medications improved until 2010 and were unchanged after that point. Additionally, use of statin therapy increased but plateaued following 2014. Investigators pointed out use of combination glucose-lowering therapy began to decline among the general population, and more severely in those with poor glycemic control, beginning after 2010.

Selvin went on to note investigators hypothesized the shift in approach may have been spurred by results of the ACCORD and ADVANCE trials, which found intensive glucose control did not result in the levels of cardiovascular benefit many had expected.

"As a result of these trials, what we may be seeing is that doctors of people with diabetes may have backed off a bit on glycemic control, with potentially damaging results," Selvin said.

This study, “Trends in Diabetes Treatment and Control in U.S. Adults, 1999–2018,” was published in the New England Journal of Medicine.