Measuring glycated hemoglobin levels may be an appropriate means of catching patients with prediabetes.…
Ronald Ackerman, MD, MPH, of Indiana University, and colleagues reported in Preventive Medicine that, HbA1c testing yielded similar probabilities for developing diabetes and heart disease as those estimated by using the 2003 American Diabetes Association definition for prediabetes. "The A1c test may provide a badly needed, clinically practical indicator of the composite risk for incident diabetes and cardiovascular disease," they wrote.
Fasting plasma glucose and two-hour plasma glucose, two commonly used tests for assessing diabetes and prediabetes, are limited because they require a patient to return on a separate day after an overnight fast and remain in the office for 2-3 hours which is a potential barrier to test completion, the researchers said.
Measuring HbA1c is easier — it requires only one blood draw. In June 2009, the International Expert Committee, which represents several major diabetes groups, recommended using HbA1c to diagnose diabetes.
The recommendations of the committee have stirred up some controversy, still, the researchers said, only about 7% of patients with prediabetes — who are thus at risk for later diabetes and heart disease — are aware of their status.
To estimate the risks of developing diabetes and cardiovascular disease for adults with different HbA1c levels, Ackerman and colleagues assessed data from the National Health and Nutrition Examination Survey (NHANES) 2003-2006.
Among adults who met the 2003 ADA definition for prediabetes, the probabilities for developing Type 2 disease over 7.5 years and cardiovascular disease over 10 years were 33.5% and 10.7%, respectively.
The researchers found that using HbA1c alone — with a range of 5.5% to 6.5% defining prediabetes — would identify a population with comparable risks for diabetes and heart disease (32.4% and 11.4%, respectively).
But using a slightly higher cutoff — beginning at 5.7% — would identify increased risks of 41.3% for diabetes and 13.3% for heart disease.
These risks are comparable to those seen in patients enrolled in the Diabetes Prevention Program, which had an enrollment criteria of both elevated fasting plasma glucose and impaired glucose tolerance, the researchers said.
Thus, they concluded, using a bottom cutoff of 5.7% for diagnosing prediabetes may be more appropriate.
Either way, they said, HbA1c measurement "should be considered a means of identifying greater numbers of patients at risk for diabetes and heart disease" — especially because "of its practical nature and wide availability."
The study was limited by its use of cross-sectional data, and it may be lacking in generalizability. For instance, a greater number of African Americans would be identified as having prediabetes than if using fasting plasma glucose or two-hour plasma glucose testing, the researchers noted.
- Explain that measuring glycated hemoglobin (HbA1c) levels may be an appropriate means of detecting patients with prediabetes.
- Note that an HbA1c in a range of 5.5% to 6.5% defines prediabetes and identifies a population with risks for diabetes and heart disease comparable to that defined using results of fasting and two-hour glucose testing.
Ackerman RT, et al "Identifying adults at high risk for diabetes and cardiovascular disease using hemoglobin A1c" Am J Prev Med 2011; 40(1): 11–17.