Application of the Continuous Glucose Monitoring System (CGMS) in the 72-hour fast test in two patients with hypoglycemia.

Objective: Hypoglycemia occurs in several pathologic states, and the supervised 72-h fast is the classic diagnostic test for hypoglycemia caused by insulinoma. The Continuous Glucose Monitoring System (CGMS), Medtronic MiniMed, Northridge, CA) is an appropriate method to detect asymptomatic hypoglycemia episodes in diabetes mellitus patients. In the present study, we use the CGMS to monitor glucose dynamics during a 72-h fast.

Methods: Two patients with hypoglycemia disorders were admitted to the hospital for testing. The CGMS sensors were inserted into the subcutaneous tissue prior to starting a 72-h fast test. Finger stick glucose levels were taken every 3-4 h, and the data were entered into the monitor for calibration.

Results: Paired glucose readings from CGMS and conventional meters were correlated significantly (P < 0.001, r2 = 0.79). There was no significant difference between the CGMS glucose levels and conventional meter glucose levels (P > 0.05). Use of CGMS detected a high prevalence of asymptomatic hypoglycemia and two types of hypoglycemia dynamics during a 72-h fast test.

Conclusions: This initial report using CGMS detected two types of hypoglycemia dynamics during 72-h fasting, which may provide clues to better understand the pathophysiology of hypoglycemia.