"This lower level of control may partly explain why blacks have disproportionately higher rates of death and complications from diabetes," said Julienne Kirk, PharmD, lead author of the study published online today (Aug. 25) in Diabetes Care.
The findings stress on the need to ascertain why there is a difference in control and to find ways to prevent and control the consequential health problems, according to Kirk.
Long-term complications like blindness, amputation and end-stage kidney failure can occur as a result of poor control of blood sugar.
Studies that measured sugar control among blacks and whites using a blood test for glycosylated hemoglobin - hemoglobin that has linked with glucose, or blood sugar, were investigated by the researchers. The body shows better blood sugar control with lower amounts of glycosylated hemoglobin, also known as A1C, in the blood.
The researchers were able to find the differences in a "meta-analysis" by combining the data from the 11 studies involving a total of 42,273 white and 14,670 black patients, which would otherwise have not shown up in each individual study. Meta-analysis of racial and ethnic differences in blood sugar control among diabetic patients was done for the first time.
The majority of the studies were based on patients aged over 50 with type II diabetes.
In this type of diabetes, there is a decrease in insulin production in the body, resulting in high levels of sugar in bloodstream.
The A1C measurement was standardized during the period 1993-2005; hence, studies done in this period were taken up for the meta-analysis. A1C measurement reveals the average blood sugar control in the last 3 months. It also gives an idea as to how well the blood sugar control plan is working, which is useful for patients and health care providers.
The level of A1C was 0.65% less in whites than blacks. It is already known that there is 21% reduction in any complication of diabetes for every 1% reduction in A1C levels. Thus, in this study, whites had 15% less chances of getting the complications than the blacks.
Minority populations may show poorer blood sugar control, according to earlier studies.
Differences in quality of care, counting the intensity of treatment; socioeconomic differences, such as being less likely to have prescription drug coverage, and genetic differences are the likely reasons for it.
The researchers said further research is required to examine these factors, as they could not it in their study.
"Although A1C control among blacks likely contributes to their elevated risk of complications, it accounts for only a portion," said Kirk, an associate professor of family and community medicine.
"We need to understand more fully why this disparity exists and to eliminate factors that may be changeable, such as improving access to care."