Standard Test for Determining Blood Sugar Control in People with Diabetes Is Not Always an Accurate Measure of Blood Sugar Control and Interpretation Differs Based on Race.
Boston, MA – June 14, 2017 – T1D Exchange, an organization that is accelerating novel treatments and improving care, today published an important research study that confirms disparities between blacks and whites in hemoglobin A1c (HbA1c) levels, the standard measure used to assess blood sugar control in people with diabetes. Racial differences in HbA1c levels have been consistently reported in adults and children with type 1 diabetes (T1D) or type 2 diabetes, with non-Hispanic blacks having higher A1c levels than non-Hispanic whites. T1D Exchange researchers sought to understand whether this difference is due to worse glycemic control in blacks or the consequence of racial differences in the glycation of hemoglobin.
This study builds upon previous T1D Exchange research that identified racial disparities in glucose control, with blacks having higher HbA1c levels than whites in both children and adults. In the scientific community, differing theories have been proposed regarding these disparities; that higher HbA1c levels in blacks represents worse glycemic control; and that higher HbA1c levels could be due to race-based genetic differences in the glycation of hemoglobin at the same glucose levels. If the latter were true, it would mean that HbA1c on average is overestimating the mean glucose concentration in blacks. Prior to this study, data to address the issue of racial differences in glycation of hemoglobin were limited. This study, designed to address this issue, was funded by the Leona M. and Harry B. Helmsley Charitable Trust and led by the Jaeb Center for Health Research in Tampa, FL, which serves as the T1D Exchange Clinic Network Coordinating Center.
Among the major results of the study is the finding that an HbA1c measurement tends to overestimate the amount of blood sugar elevation in blacks compared with whites. However, race only partially explains the observed HbA1c differences between blacks and whites.
To determine whether a racial difference exists in the association of mean glucose with HbA1c, 10 diabetes centers in the United States that are part of the T1D Exchange Clinic network enrolled 208 patients, 104 self-identified blacks and 104 self-identified non-Hispanic whites aged between 8 years and 75 years with type 1 diabetes. Each study participant wore a FreeStyle Libre Pro Flash Glucose Monitoring System, a professional continuous glucose monitoring (CGM) device, which was provided for the study by Abbott Diabetes Care. This CGM provides a measurement of the glucose level every 15 minutes for up to 14 days. Glucose measurements were made on each participant for up to 12 continuous weeks. HbA1c measurements were made at a central laboratory.
Overall, average HbA1c levels were about 0.8% higher in blacks than whites (average HbA1c 9.1% versus 8.3%). However, based on the mean glucose level, the HbA1c should have been only about 0.4% higher. This finding represents racial differences in glycation of hemoglobin, which may relate to differences in the lifespan of red blood cells.
These findings show definitively, for the first time, that HbA1c levels are higher in blacks compared with whites for a given mean glucose level. Prior to this study, no other study has had sufficient data to definitively determine whether racial differences exist in the glycation of hemoglobin.
“This study is an important effort that has the potential to change the landscape of treatment for those with type 1 diabetes,” says Richard M Bergenstal, MD, Executive Director, International Diabetes Center at Park Nicollet in Minneapolis and lead author of this study published in Annals of Internal Medicine. “While more studies are required, this study does underscore the need for clinicians to pay attention to blood glucose levels and patterns more than to HbA1c levels to really individualize care. The HbA1c is a great marker for risk for long term complications, but knowing the blood glucose levels throughout the day is how we should make diabetes management decisions with our patients.”
In addition to the racial disparity finding, the results of the current study confirm the findings of other studies that there is considerable variation in the mean-glucose-HbA1c relationship among individuals irrespective of race. For instance, an HbA1c level of 8.0% could be associated with a near-normal mean glucose in one patient and a very elevated mean glucose in another patient.
“This study exemplifies what T1D Exchange does best; design patient-centered research studies that seek to understand unmet needs with the goal of improving clinical care and outcomes for people living with type 1 diabetes,” said Dana Ball, executive director and co-founder, T1D Exchange.
In conclusion, the study results demonstrate that HbA1c levels tend to overestimate the amount of blood glucose elevation in blacks compared with whites. However, after accounting for this discrepancy, blacks still have higher HbA1c levels on average than whites. This emphasizes the need for need for future research to identify and modify barriers which impede better glycemic control in blacks with diabetes.
About T1D Exchange
T1D Exchange was founded on the belief that people affected by type 1 diabetes need better solutions faster – better treatments and better care. Our nonprofit organization takes an innovative approach that puts the community of people touched by type 1 diabetes at the center of research that will meaningfully impact their lives. Our integrated model offers researchers access to aggregated clinical, biological, patient-reported outcomes and electronic health record data, all while fostering collaboration among patients, physicians, researchers and industry. Our model is multi-faceted and complex, but our goal is simple: to tangibly improve outcomes for people with type 1 diabetes as fast as humanly possible.
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Sarah Karr, Matter Communications
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