Falsely lowered glycated hemoglobin levels in a patient with hemochromatosis and type 2 diabetes mellitus Beverly Mielke Kocarnik MD, MPH1*, Dawn DeWitt MD, MSc2, Irl B. Hirsch MD3 1Department of Internal Medicine, Residency Training Program, University of Washington School of Medicine, Box 356421, 1959 NE Pacific St, Seattle, WA, 98195, 2Rural Health Academic Centre, Melbourne Medical School, The University of Melbourne, 49 Graham Street, Shepparton VIC 3632, Australia, 3Division of Metabolism, Endocrinology, & Metabolism, University of Washington School of Medicine, 4225 Roosevelt Ave NE, Suite 101, Seattle, WA, 98105, Running title: Glycated hemoglobin and hemochromatosis Email: Beverly Mielke Kocarnik ; Dawn DeWitt ; Irl B. Hirsch ihirsch@u.washington.edu *Corresponding author: Beverly Mielke Kocarnik MD, MPH Department of Internal Medicine Residency Training Program University of Washington School of Medicine Box 356421 1959 NE Pacific Street Seattle, WA 98195 Email: bmielke@uw.edu Phone: 971-404-7060 Fax: 206-685-8652 Abstract word count: 187 Article text word count: 1166 Number of tables and figures: 2 Keywords: hemochromatosis, glycated hemoglobin, diabetes mellitus Abstract
diabetes.2 Therefore, an average primary care panel with 1,500 patients will include approximately 4 patients with both hereditary hemochromatosis and diabetes. In this report, we discuss a patient with concurrent hereditary hemochromatosis and diabetes glycated hemoglobin levels (A1C) appeared to be inaccurate relative to his home capillary blood glucose readings and fasting blood glucose values. Since the vast majority of primary care physicians will have several patients with these concurrent diseases, it is important to understand the optimal management and diabetes monitoring for such patients, especially in light of the American Diabetes Association recommendation that A1C can be used for diagnosis of diabetes.3 Case Presentation A 59 year old Caucasian male with hemochromatosis and diabetes was referred for discordant fasting blood glucose and glycated hemoglobin levels (A1C). He was diagnosed with diabetes fifteen years previously and had been treated with oral agents for several years. His A1C remained below 7% until 6 months prior to consultation. At the time of referral, he was taking metformin 1500 mg daily and glimepiride 2 mg every morning. Additional medications were hydrochlorothiazide/irbesartan 12.5 mg/300 mg daily, aspirin 100 mg daily, and sildenafil 50 mg as needed. The patient’s physical examination showed truncal obesity with a BMI of 38, but was otherwise unremarkable without hyperpigmentation.
Clinic visits A1C Glucose readings HBG or FBG1 (mmol/L) Fructosamine (Normal = umol/L) Comments July 2010 (referral information) 7.0% FBG 8-10 Hb 158 = Hct 47; ferritin = 114 Phlebotomy Aug 10, 2010 Nov 25 2010 7.4% HBG Average 8.74 + 0.98 (SD) 349 (Dec 3 2010) Sulfonylurea switched (dose equivalent actually lower); 0.6 nmol/L (0.3-3.20); BMI 38 Phlebotomy Dec 15, 2010 Jan 20 2011 Insulin glargine initiated at 10 units (bedtime) with to fasting goal < 6 mmol/L FBG Jan 31 2011 6.1% HBG Average 8.77± 0.88 (SD) Phlebotomy Jan 5, 2011 April 15 2011 6.4% Phlebotomy 3 months prior; Hb 156 = Hct 45; BMI 36. Insulin glargine dose 22 units nightly. July 17 2011 6.1% HBG Average 7.4 = 30 day meter average (25% fasting) 287 Ferritin 100; iron 27.7; Hb 155=Hct 45; MCV 90; BMI 35.6 1HBG = home blood glucose; FBG = fasting (capillary) blood glucose 6%