Can continuous glucose monitoring provide objective documentation of hypoglycemia unawareness?

OBJECTIVE

To establish criteria defining hypoglycemia as detected by the continuous glucose monitoring system (CGMS) in patients with type 1 diabetes that best predict hypoglycemia unawareness (HUN), established by a validated questionnaire.

METHODS

Adult patients were selected for inclusion in this study if they had long-standing type 1 diabetes, a fasting level of C peptide of < or = 0.6 ng/mL, commitment to achieving glycemic control, and a hemoglobin A1c value no higher than 9%. After clinical data and self-monitoring of plasma glucose data were collected, patients underwent a 72-hour glucose monitoring session with use of a Medtronic-MiniMed CGMS. The presence of HUN was determined by a questionnaire. Factors independently associated with HUN were estimated by multivariate independent analysis.

RESULTS

Our study group consisted of 60 patients (33 women and 27 men) who ranged in age from 18 to 84 years (mean, 50.4) and had had diabetes for 5 to 56 years (mean, 23.8). The best predictor of HUN was the maximal duration of hypoglycemia, as determined by the CGMS (P = 0.001). Detection of hypoglycemic episodes with a duration of more than 90 minutes identified patients who had HUN with an 88% specificity and 75% sensitivity. HUN was also significantly associated with use of angiotensin-converting enzyme inhibitors or angiotensin receptor blockers (P = 0.003) and with a longer duration of diabetes (P = 0.008).

CONCLUSION

The CGMS can be used for objective detection of patients with HUN.