Misdiagnosis of Gestational Diabetes and Hypoglycemia Using Portable Blood Glucose Meters

To the Editor .—Published recommendations indicate that self-monitoring of blood glucose levels using portable glucose meters should not be used for diagnosing diabetes. 1 Furthermore, self-monitoring may be unreliable in the hypoglycemic range. 1,2 Recently, we had the occasion to observe capillary blood glucose measurements used for falsely diagnosing gestational diabetes in one case, and for formulating a false diagnosis of hypoglycemia in another circumstance. The inaccuracy of these diagnoses was established on subsequent evaluation when assessed by laboratory determinations of blood glucose levels. Report of Cases .—Case1.—A 30-year-old Jordanian woman, 34 weeks' pregnant, was self-referred to confirm a diagnosis of gestational diabetes subsequent to a 1-hour 50-g screening test. A 3-hour 100-g glucose tolerance test was then performed in the obstetrician's office using a blood glucose meter. At the time of her consultation, a 1-hour laboratory value of 10.7 mmol/L was obtained after a 50-g glucose load.