Persistent C-peptide levels and microvascular complications in childhood onset type 1 diabetes of long duration

Aims: The aim was to determine if persistent c-peptide in long duration childhood onset (<17 years) type 1 diabetes (T1D) related to microvascular complications. Methods: Pittsburgh Epidemiology of Diabetes Complications (EDC) participants (n = 185) had serum c-peptide levels measured by Mercodia ultra-sensitive ELISA at the 25-year follow-up exam. Microvascular complications between those with and without detectable c-peptide were compared. Results: Eighteen (9.7%) participants had detectable median c-peptide levels of 3.8 (2.6, 12.2) pmol/L and did not differ from those without detectable levels. No differences in microalbuminuria, confirmed distal symmetric polyneuropathy, renal failure, or between those with one or more complications were found between the two groups. Proliferative retinopathy (PR) was marginally lower in those with detectable c-peptide (33.3% vs 55.1%, p = 0.08). However, those with c-peptide were somewhat less likely to have fasted for a full 8-h (66.7% vs. 84.9%, p = 0.09). Excluding those not fully fasted, PR no longer approached significance but macroalbuminuria became marginally lower in those with detectable levels (23.4% vs 0%, p = 0.07). Conclusions: Low levels of c-peptide in T1D patients of long duration were detected but were not strongly related to microvascular complications. (C) 2019 Elsevier Inc. All rights reserved.