Urinary C-Peptide Creatinine Ratio as a Non-Invasive Tool for Identifying Latent Autoimmune Diabetes in Adults (LADA)

Latent autoimmune diabetes in adults (LADA) is a slowly progressing form of immune-mediated diabetes that combines phenotypical features of both type 2 diabetes mellitus (T2DM) and type 1 diabetes mellitus (T1DM), meaning that accurate and early diagnosis of this subtype of diabetes is critical for optimal long-term management. Urinary C-peptide creatinine ratio (UCPCR) represents a non-invasive and practical method for assessing endogenous insulin production to facilitate diabetes classification. However, no study to date has reported the use of UCPCR in identifying LADA.

A total of 574 subjects were included in our study (42 LADA, 61 T1DM, 471 T2DM). All participants were evaluated for UCPCR and underwent clinical and laboratory evaluations. UCPCR was compared among different subtypes of diabetes using multinomial regression analysis, and a receiver operating characteristic (ROC) curve was used to identify its performance in diagnosing LADA.

UCPCR was lower in LADA (0.4±0.6 nmol/mmol) compared with T2DM (1.2±0.9 nmol/mmol), but higher than in T1DM (0.2±0.3 nmol/mmol) (p<0.05). The association between UCPCR and LADA remained significant after adjusting for gender, age, age at diagnosis, body mass index, high-density lipoprotein cholesterol, and triglyceride (OR, 95% confidence interval (CI), 0.29 (0.09, 0.95)). The ROC curve revealed an area under the curve of 0.835 (95% CI (0.742-0.928), p<0.001). The cut-off point for UCPCR ≤ 0.46 nmol/mmol was 82.1% for sensitivity and 76.7% for specificity in the diagnosis of LADA.

UCPCR may represent a non-invasive, simple, and practical measurement of insulin secretion for early discrimination of LADA in routine clinical practice.