# Serum carnosinase 1, an early indicator for incident microalbuminuria in type 1 diabetes

## TL;DR

This study shows that serum carnosinase 1 (CN1) levels can predict early kidney damage in people with type 1 diabetes.

## Contribution

The study identifies serum CN1 as a novel early predictor of microalbuminuria in type 1 diabetes.

## Key findings

- Baseline age, redox status, and NT-proBNP were associated with serum CN1 concentration.
- Middle tertile CN1 levels were linked to reduced risk of microalbuminuria after adjustments.
- Serum CN1 may serve as a new biomarker for identifying patients at risk for diabetic kidney disease.

## Abstract

Carnosinase (CN1) polymorphisms have been linked to diabetic kidney disease (DKD), as CN1 degrades dipeptides which scavenge oxidative metabolites and prevent the formation of advanced glycation end-products. In this work, we studied the association between serum CN1, the systemic redox status and long-term renal outcome in type 1 diabetes.

Serum CN1 was measured in a prospective type 1 diabetes cohort (n = 218) with a 16-year follow-up. A total of 218 patients treated at the Diabetes Outpatient Clinic of the Weezenlanden Hospital (nowadays Isala Hospital, Zwolle, The Netherlands) were included in this analysis. We assessed whether serum CN1 was associated with renal function and development of DKD as well as other diabetic complications.

At baseline, age, systemic redox status and N-terminal pro brain-natriuretic peptide (NT-proBNP) were associated with serum CN1 concentration (p < 0.05). During follow-up, CN1 concentration in the middle tertile was associated with less incident microalbuminuria (odds ratio = 0.194, 95% C.I.: 0.049—0.772, p = 0.02) after adjustment for age, systemic redox status, NT-proBNP and sex.

Serum CN1 could predict incident microalbuminuria and may be used as a novel parameter to identify patients at risk for DKD.