Racial differences in diabetes diagnostic thresholds: study

August 6, 2012

Healthcare providers should take into account differences among racial groups when using hemoglobin A1C levels to diagnose and monitor diabetes, new research from Beth Israel Deaconess Medical Center suggests.

In a study published Aug. 7 in the , researchers analyzed National Health and Nutrition Survey data from 2005 to 2008 to examine the association between hemoglobin A1C levels in black and white adults and the risk for retinopathy, an eye complication of that is detectable early in the disease and can ultimately lead to blindness.

"There have been several studies indicating that hemoglobin A1C levels are consistently higher in blacks than in whites, even though underlying are similar," said lead author Yusuke Tsugawa, MD, MPH, a primary care fellow at Beth Israel Deaconess Medical Center. "We looked at the data to determine if a higher diagnostic cutoff of A1C level should be used to diagnose diabetes in blacks than in whites, or if there should be a single cutoff for all races."

Diabetes has been historically diagnosed based on blood glucose tests, but in 2010 the International Expert Committee recommended adding hemoglobin A1C because it is a more reliable test that reflects average blood sugar over the past two to three months.

In line with the Expert Committee's recommendation, the and the subsequently adopted a hemoglobin A1C level of 6.5 percent or higher as a new diagnostic criterion for diabetes. For people who do not have diabetes, a normal hemoglobin A1C level is around 5 percent.

Given the evidence of naturally higher A1C levels in black people, the researchers expected to also find a delayed development of retinopathy in blacks compared to whites. Instead, the data showed that the A1C level where the risk of retinopathy begins to increase was paradoxically lower in black people compared to white people.

"Our study results show that the risk of diabetic retinopathy is higher for blacks at any given hemoglobin A1C level between 5 percent and 7 percent, and that the higher risk at a hemoglobin A1C level of 5.5 to 5.9 percent for blacks was comparable to the risk at a hemoglobin A1C level of 6.0 to 6.4 percent for whites," said Tsugawa. "This indicates that black people may be more vulnerable to high A1C status than whites."

Further research may bear out the team's hunch that the guidelines may serve those at risk for diabetes better if the diagnostic threshold were lowered for blacks compared to whites.

"Globally, diabetes is one of our most prevalent public health concerns, so this could have important health care delivery and health care policy implications" said Tsugawa. "It may be appropriate for doctors to more closely monitor for early diabetic complications for their black patients than for their white patients and black patients with diabetes may benefit from retinal exams at an earlier stage of their disease."

"And if future studies show that setting race-specific cutoff points for A1C is cost-effective, we might be able to trim healthcare expenditure in diabetes by targeting interventions toward specific, high-risk black populations," said Tsugawa.

The study was not able to examine how long individuals were at the observed A1C status. Since the development of retinopathy depends on both the level of elevated and the duration at that level, further studies with repeated A1C measurements would lend greater validity, and give a fuller picture of the complex associations among A1C level, duration and race.

"Another unanswered question is the underlying mechanism as to why A1C levels are consistently higher in blacks than whites," said senior author Christina Wee, MD, MPH, Associate Section Chief for Research in the Division of General Medicine and Primary Care at BIDMC. "This may be due to biological differences or socio-behavioral differences including disparities in access to health and preventive care, which often lead to dramatically different policy implications. We're unclear on the cause, but we're certain it warrants further investigation."

Explore further: Room for improvement in knowledge of ABC levels, goals

Related Stories

Room for improvement in knowledge of ABC levels, goals

April 19, 2012
(HealthDay) -- Many individuals with diabetes do not know their last hemoglobin A1C (A1C), blood pressure, and low-density lipoprotein (LDL) cholesterol levels (ABC levels), although the correlation between such knowledge ...

2 tests better than 1 to diagnose diabetes in overweight children

May 2, 2011
A new study found that the recommended blood test may not be enough to catch type 2 diabetes in overweight children, missing more than two-thirds of children at high-risk for the condition. Researchers from Children's Mercy ...

Many people with type 1 diabetes missing treatment goals: study

June 10, 2012
(HealthDay) -- Many Americans with type 1 diabetes fail to meet their treatment targets, according to researchers who analyzed data from a newly created registry that includes more than 25,000 patients at 67 clinics nationwide.

New NIH fact sheet explains test for diabetes, prediabetes

January 27, 2012
A new fact sheet from the National Institutes of Health explains the A1C test, a widely used and important test to diagnose type 2 diabetes and prediabetes, and to monitor blood glucose levels of people with type 1 and type ...

Hemoglobin A1C inadequate for postpartum diabetes screening

June 19, 2012
(HealthDay) -- For postpartum women who have had gestational diabetes mellitus (GDM), the hemoglobin A1c (A1C) test criteria alone or in combination with fasting glucose test criteria does not provide sensitive and specific ...

Elderly diabetes patients with very low glucose levels have slightly increased risk of death

April 18, 2011
A new study of older diabetes patients has found that well-controlled blood sugar levels were associated with a lower risk of major complications such as heart attacks, amputation and kidney disease, but the very lowest blood ...

Recommended for you

Personalized blood sugar goals can save diabetes patients thousands

December 11, 2017
A cost analysis by researchers at the University of Chicago Medicine shows treatment plans that set individualized blood sugar goals for diabetes patients, tailored to their age and health history, can save $13,546 in health ...

Kidney disease increases risk of diabetes, study shows

December 11, 2017
Diabetes is known to increase a person's risk of kidney disease. Now, a new study from Washington University School of Medicine in St. Louis suggests that the converse also is true: Kidney dysfunction increases the risk of ...

Type 2 diabetes is not for life

December 5, 2017
Almost half of the patients with Type 2 diabetes supported by their GPs on a weight loss programme were able to reverse their diabetes in a year, a study has found.

Skipping breakfast disrupts 'clock genes' that regulate body weight

November 30, 2017
Irregular eating habits such as skipping breakfast are often associated with obesity, type 2 diabetes, hypertension and cardiovascular disease, but the precise impact of meal times on the body's internal clock has been less ...

Type 2 diabetes has hepatic origins

November 28, 2017
Affecting as many as 650 million people worldwide, obesity has become one of the most serious global health issues. Among its detrimental effects, it increases the risk of developing metabolic conditions, and primarily type ...

Critical link between obesity and diabetes has been identified

November 28, 2017
UT Southwestern researchers have identified a major mechanism by which obesity causes type 2 diabetes, which is a common complication of being overweight that afflicts more than 30 million Americans and over 400 million ...

0 comments

Please sign in to add a comment. Registration is free, and takes less than a minute. Read more

Click here to reset your password.
Sign in to get notified via email when new comments are made.