Use of continuous glucose monitoring to estimate insulin requirements in patients with type 1 diabetes mellitus during a short course of prednisone

Abstract

Background: Insulin requirements to maintain normoglycemia during glucocorticoid therapy and stress are often difficult to estimate. To simulate insulin resistance during stress, adults with type 1 diabetes mellitus (T1DM) were given a three-day course of prednisone.

Methods: Ten patients (7 women, 3 men) using continuous subcutaneous insulin infusion pumps wore the Medtronic Minimed CGMS (Northridge, CA) device. Mean (standard deviation) age was 43.1 (14.9) years, body mass index 23.9 (4.7) kg/m(2), hemoglobin A1c 6.8% (1.2%), and duration of diabetes 18.7 (10.8) years. Each patient wore the CGMS for one baseline day (day 1), followed by three days of self-administered prednisone (60 mg/dl; days 2-4), and one post-prednisone day (day 5).

Results: Analysis using Wilcoxon signed rank test (values are median [25th percentile, 75th percentile]) indicated a significant difference between day 1 and the mean of days on prednisone (days 2-4) for average glucose level (110.0 [81.0, 158.0] mg/dl vs 149.2 [137.7, 168.0] mg/dl; p = .022), area under the glucose curve and above the upper limit of 180 mg/dl per day (0.5 [0, 8.0] mg/dl.d vs 14.0 [7.7, 24.7] mg/dl.d; p = .002), and total daily insulin dose (TDI) , (0.5 [0.4, 0.6] U/kg.d vs 0.9 [0.8, 1.0] U/kg.d; p = .002). In addition, the TDI was significantly different for day 1 vs day 5 (0.5 [0.4, 0.6] U/kg.d vs 0.6 [0.5, 0.8] U/kg.d; p = .002). Basal rates and insulin boluses were increased by an average of 69% (range: 30-100%) six hours after the first prednisone dose and returned to baseline amounts on the evening of day 4.

Conclusions: For adults with T1DM, insulin requirements during prednisone induced insulin resistance may need to be increased by 70% or more to normalize blood glucose levels.

Keywords: continuous glucose monitoring; insulin requirements; prednisone; stress; type 1 diabetes mellitus.

Figures

Figure 1

Representative CGMS® tracings from one patient with and without prednisone. Insulin doses: Day 1, 0.49 U/kg (no prednisone); Day 2, 1.09 U/kg, Day 3, 0.89 U/kg, and Day 4, 1.00 U/kg (on prednisone); Day 5, 0.86 U/kg (no prednisone).

Figure 2

(A) Box plot of median, interquartile range, and 5th and 95th percentiles for glucose average mg/dl: Day 1 vs mean Days 2–4 significantly different (p = .002). (B) Box plot of median, interquartile range, and the 5th and 95th percentiles for glucose area above the upper limit, 180 mg/dl: Day 1 vs mean Days 2–4 significantly different (p = .002). (C) Box plot of median, interquartile range, and 5th and 95th percentiles for total Insulin U/kg per day: Day 1 vs mean Days 2–4 significantly different (p = .002); Days 2–4 vs Day 5 significantly different (p = .010); Day 1 vs Day 5 significantly different (p = .003).