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JAMA Diagnostic Test Interpretation
February 9, 2016

HbA1c in the Evaluation of Diabetes Mellitus

Author Affiliations
  • 1Division of Endocrinology, Diabetes, Metabolism and Nutrition, Department of Medicine, Mayo Clinic, Rochester, Minnesota
  • 2Division of Endocrinology, Department of Medicine, National University of Ireland, Galway, Ireland
  • 3Knowledge and Evaluation Research Unit, Division of Endocrinology, Diabetes, Metabolism and Nutrition, Department of Medicine, Mayo Clinic, Rochester, Minnesota
JAMA. 2016;315(6):605-606. doi:10.1001/jama.2015.16561

A 76-year-old man presented to his physician’s office, requesting assistance managing his type 2 diabetes. He was diagnosed 18 months previously, based on a fasting blood glucose level of 200 mg/dL (11 mmol/L), and was prescribed metformin. The metformin was discontinued 12 months later, when his hemoglobin A1c (HbA1c) was 6.4% (46 mmol/mol). He had a history of hypertension, hereditary spherocytosis, and cholecystectomy. Medications included aspirin, atorvastatin, and lisinopril-hydrochlorothiazide. His body mass index was 38 (calculated as weight in kilograms divided by height in meters squared), blood pressure was 126/64 mm Hg, and clinical examination results were normal. He reported polyuria and polydipsia. His fingerstick blood glucose diary showed consistent recordings of greater than 350 mg/dL. His laboratory data are shown in Table 1.

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