Falsely Decreased HbA1c in a Type 2 Diabetic Patient Treated with Dapsone.

OBJECTIVE: To discuss a case of a falsely low hemoglobin A1c (HbA1c) in a transplant patient treated with dapsone and its implications. HbA1c is widely used as a measure of glycemic control in diabetic patients. With the increasing transplant population, it is important to be mindful of medications used in this population that can affect HbA1c and to use other measures of glycemic control to guide treatment decisions.
METHODS: We present details of the case and review the relevant literature.
RESULTS: A 61-year-old patient received a liver transplant in 2012 and subsequently was noted to have a falling HbA1c despite evidence of hyperglycemia based on fingerstick glucose and fructosamine measurements. Review of the medical records revealed that the discordance between HbA1c and fingerstick glucose levels developed after initiation of dapsone therapy. Dapsone may lead to a falsely low HbA1c via several mechanisms. Upon cessation of dapsone therapy, the patient's HbA1c returned to pre-dapsone levels.
CONCLUSION: It is important to be aware of medications commonly used in transplant patients that may lead to a falsely low HbA1c level so that incorrect treatment decisions are not made. Fructosamine correlates with HbA1c and can be used as a measure of glycemic control in transplant patients when HbA1c cannot be used.