Residual C-peptide secretion is associated with better CGM-metrics in adults with short-lasting type 1 diabetes

Aim: To investigate whether the risk of hypoglycemia is associated with residual β-cell function in adults with type 1 diabetes (T1D). Methods: This cross-sectional study included 61 subjects with T1D of <15 years' duration using continuous glucose monitoring (CGM). Random C-peptide levels were compared between participants with time below range (TBR) ≥3 % (n = 15) and TBR <3 % (n = 45). The associations of C-peptide levels with other CGM metrics and clinical characteristics of the study participants were also tested. Analyses were adjusted for disease duration. Results: Median [25th - 75th percentiles] C-peptide levels were generally low: 49.3 [15.7-152] pmol/L. Participants in the low-TBR group had significantly higher C-peptide levels compared to those in the high-TBR group (52.9 [19.5-176.3] vs. 21.0 [9.4-106.6] pmol/L, p = 0.036), independently from disease duration. Higher C-peptide levels were associated with better CGM-metrics (p < 0.05). A C-peptide threshold of 15.1 pmol/L was the best cut-off to distinguish people at high risk of hypoglycemia. Conclusions: C-peptide microsecretion is associated with a low risk of hypoglycemia and improved CGM metrics. Therapeutic approaches aimed at preserving minimal C-peptide secretion could potentially enhance glycemic outcomes and reduce hypoglycemic risk in individual with T1D.