Excess weight gain during insulin pump therapy is associated with higher basal insulin doses

Background: While higher total daily dose (TDD) of insulin has been associated with excess weight gain on insulin pump therapy, the role of higher total basal dose (TBD) of insulin on weight gain has not been studied. We evaluated the impact of higher TBD on weight gain in relationship to glycosylated hemoglobin (HbA1c), hypoglycemic episodes, and change in body mass index (BMI) z score in a group of pediatric patients with type 1 diabetes mellitus (T1DM). Methods: One-year data from 91 (54 Female/37 Male) patients (2.3-17.8 years of age), transitioned from basal-bolus regimen to insulin pump therapy were reviewed. Patients were divided into two groups based on changes in BMI z score: Group 1 (no change or decrease) and Group 2 (increase). Results: Thirty-three patients in Group 1 and 58 patients in Group 2. The two groups had similar TDD (0.9 +/- 0.2 vs. 0.8 +/- 0.2 U/kg/day), however Group 1 had a higher bolus: basal insulin ratio (1.8 +/- 0.6 vs. 1.5 +/- 0.6, p < 0.05). While Groups 1 and 2 had similar HbA1c values (7.7 +/- 0.7 vs. 7.70 +/- 0.6 %; p = 0.79) and activity levels (2.2 +/- 0.6 vs. 2.2 +/- 0.7; p = 0.15), Group 2 had higher rates of hypoglycemic episodes (1.0 +/- 0.4 vs. 1.5 +/- 0.9, p < 0.01). Conclusion: Excess weight gain was associated with lower bolus to basal insulin ratios independent of glycemic control and activity level. Evaluation of bolus and basal insulin doses during insulin therapy is warranted in order to avoid excess weight gain.