Unreliable Fingerstick Glucose Measurement in Systemic Sclerosis

ABSTRACT Objective: A female with systemic sclerosis was found to have apparent hypoglycemia on fingerstick blood glucose measurements while being asymptomatic. Methods: Clinical assessment, laboratory studies, and glucose-meter testing performed in clinic presented in addition to a brief literature review. Results: Per glucometer, glucose measurements increased with more proximal blood sampling on the right upper extremity, revealing values of 33, 68, and 77 mg/dL. Simultaneous venous laboratory blood glucose was 89 mg/dL. In addition, an evaluation for possible insulinoma yielded negative laboratory values. Conclusion: Certain conditions of impaired microcirculation can result in a spurious discrepancy between capillary glucose values and venous plasma glucose concentrations, a state known as pseudohypoglycemia. Awareness of damaged microvasculature in connective tissue disorders may prevent unnecessary workup of pseudohypoglycemia.