Residual Secretion of C-Peptide in Type 1 Diabetes Mellitus: What is Its Metabolic Impact?

Abstract

Abstract Background and aims: Residual C-peptide secretion, an indirect measure of endogenous insulin secretion, has been associated with better clinical outcomes. The purpose of this work was to estimate the effect, in T1DM patients, of measurable C-peptide on different CGM metrics and complications. Methods: Retrospective descriptive study of 112 T1DM patients under intensive insulin therapy, divided into individuals with non-detectable (< 0,05 ng/ml) vs detectable (≥ 0,05 ng/ml) fasting C-peptide. Data were analysed using SPSS v.27. Adjustment for covariates was assessed via linear or logistic regression for continuous or binary outcomes, respectively. Results were considered significant if p < 0.05. Results: Median age at diagnosis and duration of diabetes was 22 (12-34) and 18.5 (12-29) years, respectively. Patients with detectable C-peptide had shorter disease duration (14 [9-24] vs 20 [14-32] years, p = 0.004) and older age (27.5 [16.5-38.5] vs17.5 [9.8-28.8] years, p = 0.002). After adjustment for covariates (sex, disease duration, BMI and use of CSII), preserved C-peptide was associated with lower TAR (aβ = -11.03, p = 0.002), GMI (aβ = -0.55, p= 0.024), average glucose (aβ = -14.48, p= 0.045) and HbA1c (aβ = -0.41, p = 0.035). A statistically significant higher TIR was present in patients with measurable C-peptide, even before adjustment (β = 7.13, p = 0.044 vs aβ = 11.42, p = 0.001). No associations were found with TBR, CV and acute and chronic complications. Discussion and conclusions: Persistent C-peptide secretion in T1DM patients was associated with significantly better metabolic control translated into different metrics, namely TIR, TAR, GMI, and HbA1c.