Endocrine Abstracts

Background: Residual C-peptide (CP) secretion has been associated with better glycemic control in patients with type 1 diabetes (T1D).

Aim: To evaluate how residual fasting CP (fCP) secretion impacts glycemic control in T1D and to identify possible confounding factors.

Methods: A retrospective analysis of adult patients with T1D followed in our department that had their fCP and glucose levels obtained on the same blood sample during the year 2019. Patients with glucose <70 mg/dl were excluded. fCP <0.2 ng/ml was considered as an indicator of absolute insulin deficiency.

Results: 98 patients were included:69 (70.4%) with fCP <0.2 ng/ml and 29 (29.6%) with fCP ≥0.2 ng/ml. Patients with fCP ≥0.2 ng/ml had higher age at diagnosis (35.6 ± 10.0 vs 21.8 ± 12.0 year-old; P < .001); all of them were diagnosed after 18 years of age (vs 53.6% in the group with fCP <0.2 ng/ml). This group also had fewer patients on functional insulin therapy (FIT) (20.7% vs 42%; P < .001), lower daily doses of insulin (0.5 ± 0.2 vs 0.6 ± 0.2 UI/kg/day; P = .040) and higher HbA1c variation in the last 2 years(1.7 ± 1.3% vs 1.0 ± 0.6%; P = .001). No differences were observed when comparing this groupwith fCP <0,2 ng/ml group in terms of disease’s duration, current HbA1c, median HbA1c in the last 2 years and current BMI. In the subgroup of patients using FIT, the ones with fCP ≥0,2 ng/ml had lower current HbA1c (7.0 ± 0.5% vs 7.9 ± 0.9%; P = .005); no differences were observed when comparing with fCP <0.2 ng/ml patients in terms of disease’s duration, daily insulin dose (UI/Kg/day) and HbA1c variation in the last 2 years. In the subgroup of patients not on FIT, the ones with fCP ≥0,2 ng/ml had higher medianHbA1c (8.7 ± 2,2 vs 7.8 ± 0.8%; P = .033) and HbA1c variation in the last 2 years (1.9 ± 1.4 vs 1.9 ± 0.7%; P = .002); no differences were observed when comparing with fCP <0.2 ng/ml patients in terms of disease’s duration and daily insulin dose. In adjusted multivariate analysis, higher age at diagnosis was an independent predictor of fCP ≥0.2 ng/ml (ORa 1.091; P = .012).

Conclusions: Our findings suggest that patients with fCP ≥0.2 ng/ml doing FIT have better glycemic control than the ones with FIT and fCP <0.2 ng/ml. Nevertheless, that association was not found in patients with fCP ≥0.2 ng/ml without FIT. Thus, the potential benefit of persistent CP secretion seems to be dependent on the therapeutic scheme instituted. Additionally, it has been shown that higher age at diagnosis was a predictor for long-term fCP secretion. Therefore, we should try to implement FIT in all patients, although higher age at diagnosis might have the most potential advantage.