Benefits of an insulin dosage calculation device for adolescents with type 1 diabetes mellitus

Objective: Multiple daily injection insulin regimens (MDI) and continuous subcutaneous insulin infusion (CSII) allow adolescents with type 1 diabetes mellitus (DM) meal flexibility, and may improve metabolic control. The insulin dosage calculations, however, involve ratios of insulin to carbohydrate and corrections for high blood glucose values, and are labor-intensive and prone to error. We evaluated the impact of an insulin dosage calculation device (IDC) on metabolic control, treatment satisfaction, regimen adherence and quality of life in adolescents using MDI or CSII. Research Design and Methods: We conducted a randomized control trial using the IDC in 83 adolescents on MDI or CSII. At enrollment, patients received training on dosage calculation using either the IDC or conventional methods, and performed sample calculations. At enrollment, 6 months and 12 months, we recorded HbA_1c and frequency of hypoglycemia, and patients completed questionnaires assessing treatment satisfaction, regimen adherence and quality of life. After 6 months, patients in the control group were also given the IDC. Results: We observed a higher frequency of errors with conventional calculations (53-67% incorrect calculations) than with the IDC (25-32% incorrect). At 6 months, there was a trend toward improved HbA_1c in the IDC group overall (9.3 vs 8.9, p = 0.07) and a significant improvement in the subset (42%) who used the IDC consistently (9.7 vs 8.8, p = 0.03). There was no change in HbA_1c in the control group during this interval (9.0 vs 8.9, p = 0.90). During months 6-12, when both groups were combined, there was a significant increase in HbA_1c in patients using the IDC inconsistently or not at all (8.9 vs 9.4, p = 0.005), but no change in HbA_1c in those using the IDC consistently (9.1 vs 8.9, p = 0.57). Treatment satisfaction, adherence and quality of life improved throughout the study in both groups. Conclusions: Errors in calculation of insulin dosage by adolescents occur frequently. Consistent use of an insulin dosage calculation device may help to improve metabolic control in adolescents using MDI or CSII.