Prevention of hypoglycemia during exercise in children with type 1 diabetes by suspending basal insulin

Abstract

Objective: Strategies for preventing hypoglycemia during exercise in children with type 1 diabetes have not been well studied. The Diabetes Research in Children Network (DirecNet) Study Group conducted a study to determine whether stopping basal insulin could reduce the frequency of hypoglycemia occurring during exercise.

Research design and methods: Using a randomized crossover design, 49 children 8-17 years of age with type 1 diabetes on insulin pump therapy were studied during structured exercise sessions on 2 days. On day 1, basal insulin was stopped during exercise, and on day 2 it was continued. Each exercise session, performed from approximately 4:00-5:00 p.m., consisted of four 15-min treadmill cycles at a target heart rate of 140 bpm (interspersed with three 5-min rest breaks over 75 min), followed by a 45-min observation period. Frequently sampled glucose concentrations (measured in the DirecNet Central Laboratory) were measured before, during, and after the exercise.

Results: Hypoglycemia (< or = 70 mg/dl) during exercise occurred less frequently when the basal insulin was discontinued than when it was continued (16 vs. 43%; P = 0.003). Hyperglycemia (increase from baseline of > or = 20% to > or = 200 mg/dl) 45 min after the completion of exercise was more frequent without basal insulin (27 vs. 4%; P = 0.002). There were no cases of abnormal blood ketone levels.

Conclusions: Discontinuing basal insulin during exercise is an effective strategy for reducing hypoglycemia in children with type 1 diabetes, but the risk of hyperglycemia is increased.

Figure 1. Plasma Glucose Concentrations during/following Exercise (N=98 visits from 49 subjects)

Black dots denote mean values and boxes denote median, 25^th and 75^th percentiles.

Figure 2. Nadir and Post-Exercise Plasma Glucose Concentrations by Baseline Level (N=98 visits from 49 subjects)

The nadir glucose concentration during exercise (A) and glucose concentration 45 minutes after completion of exercise (B) are shown by baseline level. Dashed lines denote the hypo- and hyperglycemia thresholds of 70 and 200 mg/dL, respectively. Note different scales on the horizontal and vertical axes.