Residual Beta-Cell Function May Protect Kidneys in Type 1 Diabetes

Miriam E. Tucker, for Medscape

January 18, 2023

The study covered in this summary was published in Research Square as a preprint and has not yet been peer reviewed.

Key Takeaways

  • Nearly two thirds of Brazilian study participants with childhood-onset type 1 diabetes had residual pancreatic beta-cell function — as indicated by some detectable C-peptide function — more than 3 years after diagnosis.

  • Even this minimal detectable C-peptide level appeared to protect against albuminuria regardless of A1c or diabetes duration. 

Why This Matters

  • The relationship between residual beta-cell function and chronic diabetes complications isn't clear.

Study Design

  • Cross-sectional observational study with 138 adults (58.7% men) with type 1 diabetes for 3 years or longer.

  • Mean age at type 1 diabetes diagnosis was 9 years, median age at study start was 26 years, diabetes duration was 17 years, and mean A1c was 67 mmol/mol (8.3%).

  • Clinical variables, metabolic variables, and microvascular complications were compared between 59.4% of participants with some detectable C-peptide (defined as ultra-sensitive fasting serum C-peptide > 1.15 pmol/L; FCP+) and 40.6% of participants with no detectable C-peptide (< 1.15 pmol/L; FCP-).

Key Results

  • Nephropathy was present in 19.6% of total participants, at 13.4% for FCP+ versus 28.6% for FCP- (P = .03).

  • There were no significant differences in neuropathy (2.9% total, 2.4% FCP+, 3.6% FCP-; P = 1.0) or retinopathy (3.6% total, 2.4% FCP+, 5.4% FCP-; P = .3). 

  • There was a significant positive association between FCP+ and age at type 1 diabetes diagnosis (P = .039) and a significant negative association with disease duration (P = .002).

  • The probabilities of being FCP+ at 5, 10, and 20 years after type 1 diabetes diagnosis were 75%, 64.5%, and < 50%, respectively.

  • Each year of increased diabetes duration corresponded with an 8% reduction in the probability of being FCP+ (odds ratio, 0.92).

  • After adjustment for covariates, there was a lower prevalence of albuminuria among those who were FCP+ versus FCP- (13.4% vs 28.6%; P = .031).

  • Participants without nephropathy were 2.5 times more likely to be FCP+ than those with nephropathy.   


  • Small sample size.

  • Cross-sectional data.

  • Use of FCP rather than stimulated C-peptide.

  • Low prevalence of chronic complications.


  • Study funding: None.

  • Author disclosures: None.

This is a summary of a preprint research study, "Residual β-cell function in long-duration Brazilian type 1 diabetes is associated with a low prevalence of nephropathy," by Monica Andrade, Federal University of São Paulo, Brazil, and colleagues. The study has not yet been peer reviewed. 


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