Abstract #1397695: Use of Continuous Glucose Monitoring to Solve the Mystery of Pseudohypoglycemia

Abstract

Hypoglycemia (glucose < 55 mg/dL) is uncommon in people without diabetes. Routine monitoring of blood glucose in hospitalized patients usually is performed by fingerstick point of care (POC) glucose testing via glucometer as a measure of capillary whole-blood glucose, correlating with venous plasma glucose. Pseudohypoglycemia is a consideration when POC glucose is low but plasma blood glucose is normal range. It can occur in the setting of impaired peripheral perfusion, such as in patients with Raynaud’s disease, shock, or peripheral vascular disease (PVD). A 63-year-old female was admitted for evaluation of uncontrolled hypertension. Her medical history was significant for previous myocardial infarction, atrial fibrillation, and heart failure with preserved ejection fraction. She had no history of Raynaud's phenomenon, diabetes (HbA1C 5.1%), or known PVD. During hospitalization, she had symptoms of anxiety, diaphoresis, tremors, nausea, forgetfulness, dizziness. POC glucose was 37 mg/dL and the patient was promptly treated with IV dextrose, negating a blood draw for a confirmatory venous plasma glucose. Several similar episodes occurred, even while on dextrose infusion prompting a hypoglycemia laboratory work-up. Off of dextrose, her POC glucose dropped to <50 mg/dL with insulin 97.7 uIU/mL, C-peptide 12.3 ng/mL and proinsulin of 77 pmol/L. However venous glucose was 173 ng/mL and thought to reflect treatment with dextrose prior to the blood draw. A second time, POC glucose was <50 ng/mL with insulin 48.9 uIU/mL and C-peptide 6.0 ng/mL which could support hyperinsulinemia but, again, venous plasma glucose was normal (113 mg/dL). Anti-diabetic medication and insulin antibody screening were negative. A continuous glucose monitoring system (CGMS) was placed on her abdomen to provide alternative peripheral glucose data. The patient manifested glucoses of 32/15/21 mg/dL by glucometer while simultaneous CGMS values were 110/126/156 mg/dL, confirming pseudohypoglycemia. In nondiabetic patients, hypoglycemia fulfilling Whipple’s triad be documented prior to initiating the complex evaluation for causes of hypoglycemia. Our patient is unusual because she did not have usual causes of pseudohypoglycemia such as Raynaud’s disease, diabetes, shock, or PVD. The inaccuracy of POC glucose measurements in patients with impaired microperfusion should be considered when the data are incongruent, as this can cause unnecessary investigations and prolonged length of stay. Should alternative blood glucose monitoring be required in these patients, CGM is a valuable technology.