Objective: Fasting C-peptide levels are used to differentiate type 1 from type 2 diabetes (T2D), thereby determining eligibility for coverage of continuous subcutaneous insulin infusion (CSII) for patients with T2D.
Methods: A total of 168 patients (74 female/94 male, aged 55.5 ± 9.7 years) were randomized to CSII, and 163 patients (77 female/86 male, aged 56.4 ± 9.5 years) were randomized to multiple daily injections (MDI) of insulin and grouped by baseline C-peptide level: group A (≤183 pmol/L [≤0.55 ng/mL]); group B (>183 pmol/L [>0.55 ng/mL]). At 6 months, the MDI group crossed over to CSII. Within- and between-group comparisons were recorded at 6 and 12 months in the entire group and separately for those patients aged ≥65 years.
Results: CSII reduced hemoglobin A1c (A1c) equally in groups A ( P = .0006, P = .0022) and B ( P<.0001, P<.0001) at 6 and 12 months, respectively. There was an increase in weight in group A versus group B at 6 months but not 12 months ( P<.03). CSII therapy reduced total daily dose (TDD) of insulin and improved treatment satisfaction similarly in groups A and B. The results for patients aged ≥65 years displayed a similar trend as the entire group.
Conclusion: A1c, TDD of insulin, and treatment satisfaction improved for T2D patients using CSII versus MDI therapy, irrespective of baseline C-peptide level. A subgroup of patients aged ≥65 years displayed a similar trend. These results support abandoning C-peptide as a criterion for reimbursing CSII therapy in patients with diabetes.
Abbreviations: A1c = hemoglobin A1c; CMS = Centers for Medicare and Medicaid Services; CSII = continuous subcutaneous insulin infusion; DTSQ = Diabetes Treatment Satisfaction Questionnaire; MDI = multiple daily injections; RCT = randomized controlled trials; T1D = type 1 diabetes; T2D = type 2 diabetes; TDD = total daily dose.