A Novel Analytical Method for Assessing Glucose Variability: Using CGMS in Type 1 Diabetes Mellitus

Background: Marked blood glucose (BG) fluctuations may increase the risk of some complications associated with diabetes. Acute BG excursions are common in patients with diabetes, but are not usually quantified, nor can they be captured by glycosylated hemoglobin level. This study evaluated the sensitivity of novel analytical methods for assessing BG variability using CGMS (Medtronic Minimed, Northridge, CA) data from patients treated with pramlintide, a drug that acutely reduces postprandial hyperglycemia when added to insulin therapy.

Methods: Retrospective analyses were done on 24-h CGMS profiles obtained from 22 evaluable subjects with type 1 diabetes using insulin pumps and receiving preprandial three times daily injections of placebo (n = 6) or 30 microg of pramlintide (n = 16) for 4 weeks. CGMS data were recorded at baseline, after 4 weeks of treatment, and after 2 weeks off-treatment. Three parameters were calculated for each time period: variability (BG rate of change), an index for severe hypoglycemia [low BG index (LBGI)], and an index for marked hyperglycemia [high BG index (HBGI)].

Results: The mean postprandial BG rate of change was significantly lower after 4 weeks of pramlintide treatment compared with placebo treatment (0.87 vs. 1.21 mg/dL/min, P < 0.01) without changes in average glycemia, illustrating the sensitivity of this parameter to medication effects. The HBGI and LBGI indicated a decreased risk of hyperglycemia without a significant increase in risk of hypoglycemia after 4 weeks of pramlintide.

Conclusions: These results suggest the potential utility of several novel methods for assessing variability and glycemic extremes to gauge the effects of pharmacological interventions not captured by glycosylated hemoglobin.