Delay in Diagnosis of Diabetes Mellitus Due to Inaccurate Use of Hemoglobin A1C Levels

Abstract

Testing of hemoglobin A 1C (HbA 1C ) levels has become widespread in the management of patients with diabetes mellitus. Since the 1980s, it has proven to be an invaluable tool correlating with a patient's average blood glucose levels as well as with their disease morbidity. Clinicians often base treatment decisions and make adjustments depending on a patient's HbA 1C Case PresentationMrs. J, a 43-year-old woman, presented to the family medicine clinic for her annual wellness examination. She had no active complaints and was feeling fine. Her past medical history was significant for gestational diabetes, hyperlipidemia, fatty liver, hereditary spherocytosis, and borderline diabetes. She reported a 30 pack-year smoking history, and her medications included folic acid, a daily multivitamin, and fenofibrate. At the time of evaluation, her physical examination was unremarkable. Review of her laboratory data showed a fasting glucose of 187 mg/dL, a hemoglobin of 10.6 g/dL, a hematocrit of 0.273, a total bilirubin of 2.4 mg/dL, and a HbA 1C of 0.048. The remainder of the results from her laboratory examinations was not clinically significant. Further review of her medical record revealed that her low hemoglobin and hematocrit as well as her elevated bilirubin were stable and consistent with her diagnosis of hereditary spherocytosis. Of particular note, her fasting glucose was well over the diagnostic cutoff for diabetes mellitus (Table 1). Further review of her chart showed that Mrs. J had multiple fasting glucose values in the diabetic range dating back to 4 years before her current evaluation but was never diagnosed with diabetes mellitus. Over the last 2 years, her fasting glucose had ranged from 170 to 192 mg/dL (Table 2). Her HbA 1C over this same period was consistently less than 0.05. Given her persistently elevated fasting glucose levels, Mrs. J was diagnosed with diabetes mellitus despite her This article was externally peer reviewed.

Glycosylated haemoglobin: a false sense of security

“…A similar case is described by Arnold and McGowan 16. They report a delay in diagnosis of diabetes in a patient with known HS, owing to false reassurance from HbA1c levels.…”

Pitfalls in Hemoglobin A1c Measurement: When Results may be Misleading

“…19 Other conditions associated with decreased red cell turnover are also associated with falsely elevated A1c including vitamin B-12 and folate deficiency anemias, and asplenia. 20,21 There are conflicting reports regarding the effects of recent red blood cell transfusion on A1c. Traditionally, the perception has been that exposure of red cells to the high glucose concentrations of the storage medium results in a falsely elevated A1c in the transfused patient.…”

Patient safety systems in the primary health care of diabetes—a story of missed opportunities?

“…There is a wide literature on the primary care of people with diabetes that has no explicit mention of the prevention of medical error. There are also many published case reports, such as those by Arnold and McGowan [18] and Gill et al . [19]—but unusual cases do not constitute the evidence required to inform the implementation of patient safety systems.…”