Although blood glucose levels obtained by self-monitoring using a blood glucose meter are extremely important in the day-to-day management of diabetes, hemoglobin A]c is accepted as the best measure of overall blood glucose control. This test has been used in all the major research studies that examined the relationship between glycemic control and complications. HbA]c provides a measure of average blood glucose level over the preceding 2-3 months (Table 2).
It is recommended that HbA,c be checked every 6 months in patients who are currently achieving blood glucose treatment goals and if the therapeutic regimen is stable. More frequent monitoring is recommended in those individuals who do not meet these criteria. For the majority of patients, checking HbA,c every 3 months would be prudent. In most laboratories in the United States, the
Table 2 Relationship Between Hemoglobin Alc (HbA1c) and Mean Blood Glucose Level
Hemoglobin Alc (%)
Mean blood glucose level (mg/dl)
90 120 150 180 210 240 300 330
normal range for individuals who do not have diabetes is approximately 4-6%. The goal for patients with diabetes is an HbA,c level less than 7%, with action suggested if the value is more than 8%.
Comment: The standards for HbAlc and blood glucose levels are the same for patients with type 1 and type 2 diabetes. It is well known, however, that the risk of hypoglycemia that accompanies very tight blood glucose control is much greater in patients with type I than in those with type 2 diabetes. With this in mind, the standards need to be individualized for each patient. A prior history of significant hypoglycemia is an important factor in setting the goal for blood glucose control. In addition, the goal should be achievable to prevent patient discouragement. A reduction of HbA]c from 10 to 8% is very significant clinically and should be positively reinforced even though the stated goal of less than 7% has not yet been achieved.
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