Erroneous reduction of HbA1c levels in patients with type 2 diabetes mellitus on dapsone treatment for Hansen’s disease - a single-center retrospective cohort study

Abstract

Background: Dapsone treatment may reduce HbA1c levels in patients with diabetes. Aims: To assess the prevalence and characteristics of dapsone associated reduction of HbA1c in patients with Hansen’s disease. Methods: A retrospective data review of outpatient and inpatient charts of consecutive patients with Hansen’s disease and type 2 diabetes mellitus was conducted over two years from January 2014 to January 2016 at the Department of Dermatology, CMC Vellore, India. Results: Of the 245 patients with a confirmed diagnosis of Hansen’s disease who were on oral dapsone 100 mg/day as part of their treatment regimen, 49 patients had diabetes and were eligible for the study as per predetermined inclusion criteria. Of these, 35 subjects (71%) had an HbA1c discordantly lower than the corresponding mean plasma glucose levels. Patients with discordant HbA1c levels were more likely to be male and to have a higher RBC mean corpuscular volume (MCV). A greater reduction in HbA1c levels was seen during the initial 3 months of therapy of dapsone treatment. Limitations: The small sample size and retrospective design were limitations of this study. Also, we did not analyze the role of methemoglobinemia or the utility of alternative measures of glycemic control in these patients. Conclusion: We describe a high prevalence of dapsone associated inappropriate HbA1c lowering in type 2 diabetes mellitus patients. This may have serious implications for the management of diabetes in patients on therapy with dapsone.

Interpretation of HbA1c lies at the intersection of analytical methodology, clinical biochemistry and hematology (Review)

“…At the same fasting blood glucose concentration, the HbA1c discordant group had a significantly lower hemoglobin A1c value (mean HbA1c, 4.4±1.8%) compared with the HbA1c consistent group (mean HbA1c, 7.9±2.1%). During the first 3 months of dapsone therapy, the HbA1c levels decreased considerably (65).…”

“…Likewise, conflicting information on vitamin C intake and glycated Hb levels can be found in the literature (56,62,63). Additionally, other drugs, such as dapsone, sulfasalazine, antiretrovirals and ribavirin can increase the hemolysis rate, thus reducing glycated Hb levels (64)(65)(66)(67)(68). In a retrospective review of 49 individuals with T2DM and Hansen's illness, 35 patients (71%) had HbA1c readings lower than the mean blood glucose levels (65).…”

“…Additionally, other drugs, such as dapsone, sulfasalazine, antiretrovirals and ribavirin can increase the hemolysis rate, thus reducing glycated Hb levels (64)(65)(66)(67)(68). In a retrospective review of 49 individuals with T2DM and Hansen's illness, 35 patients (71%) had HbA1c readings lower than the mean blood glucose levels (65). At the same fasting blood glucose concentration, the HbA1c discordant group had a significantly lower hemoglobin A1c value (mean HbA1c, 4.4±1.8%) compared with the HbA1c consistent group (mean HbA1c, 7.9±2.1%).…”