Kids with type 1 diabetes with residual C peptide encounter lower complications: Lancet

The study, published in The Lancet Diabetes & Endocrinology, further stated that polygenic risk of type 1 and type 2 diabetes impacted residual random serum C-peptide. Even low residual random serum C-peptide concentrations seemed associated with a beneficial complications profile.

Previous studies have shown that many type 1 diabetes patients have circulating C-peptide years after the diagnosis, contrary to the presumption that type 1 diabetes leads to an absolute insulin deficiency. Minna Harsunen, Folkhälsan Research Center, Biomedicum Helsinki, Helsinki, Finland, and colleagues studied factors affecting random serum C-peptide concentration in patients with type 1 diabetes and the association with diabetic complications.

The research included people newly diagnosed with type 1 diabetes from Helsinki University Hospital in Helsinki, Finland, with repeated measurements of random serum C-peptide and concomitant glucose within three months of diagnosis and at least one year after. The long-term cross-sectional analysis involved data from participants from 57 centres in Finland diagnosed with type 1 diabetes after five years of age, a C-peptide concentration of less than 1·0 nmol/L, and initiation of insulin treatment within one year from diagnosis and patients from the DIREVA study with type 1 diabetes.

The researchers tested the association of random serum C-peptide concentrations and polygenic risk scores with one-way ANOVA and the association of random serum C-peptide concentrations, clinical factors, and polygenic risk scores with logistic regression.

The longitudinal analysis comprised 847 participants below 16 and 110 aged 16 years or older. The cross-sectional study included 645 participants from DIREVA 3984 from FinnDiane.

The study revealed the following findings:

• In the longitudinal analysis, age at diagnosis strongly correlated with the decline in C-peptide secretion.
• In the cross-sectional analysis, at a median duration of 21·6 years, 19·4% of 3984 FinnDiane participants had residual random serum C-peptide secretion (>0·02 nmol/L), which was associated with lower type 1 diabetes polygenic risk compared with participants without random serum C-peptide.
• Random serum C-peptide was inversely associated with hypertension, HbA1c, and cholesterol but also independently with microvascular complications (adjusted OR 0·61 for nephropathy; 0·55 for retinopathy).

"Our findings showed that although children with multiple autoantibodies and HLA risk genotypes rapidly progressed to absolute insulin deficiency, many adults and adolescents had residual random serum C-peptide decades after the diagnosis," the researchers concluded.

Reference:

The study "Residual insulin secretion in individuals with type 1 diabetes in Finland: longitudinal and cross-sectional analyses" was published in The Lancet Diabetes & Endocrinology.

DOI: https://doi.org/10.1016/S2213-8587(23)00123-7