Validation of a single-sample urinary C-peptide creatinine ratio as a reproducible alternative to serum C-peptide in patients with Type 2 diabetes

Diabet Med. 2012 Jan;29(1):90-3. doi: 10.1111/j.1464-5491.2011.03428.x.


Aims: Serum C-peptide can be used in Type 2 diabetes as a measure of endogenous insulin secretion, but practicalities of collection limit its routine clinical use. Urine C-peptide creatinine ratio is a non-invasive alternative that is stable for at least 3 days at room temperature in boric acid preservative. We aimed to assess the utility of urine C-peptide creatinine ratio in individuals with Type 2 diabetes as an alternative to serum C-peptide.

Methods: We assessed, in 77 individuals with Type 2 diabetes, the reproducibility of, and correlations between, fasting and postprandial urine C-peptide creatinine ratio and serum C-peptide, and the impact of renal impairment (estimated glomerular filtration rate < 60 ml min(-1) 1.73 m(-2)) on these correlations.

Results: Urine C-peptide creatinine ratio was at least as reproducible as serum C-peptide [fasting coefficient of variation mean (95% CI): 28 (21-35)% vs. 38 (26-59)% and 2-h post-meal 26 (18-33)% vs. 27 (20-34)%. Urine C-peptide creatinine ratio 2 h post-meal was correlated with stimulated serum C-peptide, both the 2-h value (r = 0.64, P < 0.001) and the 2-h area under the C-peptide curve (r = 0.63, P < 0.001). The association seen was similar in patients with and without moderate renal impairment (P = 0.6).

Conclusions: In patients with Type 2 diabetes, a single urine C-peptide creatinine ratio is a stable, reproducible measure that is well correlated with serum C-peptide following meal stimulation, even if there is moderate renal impairment. Urine C-peptide creatinine ratio therefore has potential for use in clinical practice in the assessment of Type 2 diabetes.

Publication types

  • Comparative Study
  • Research Support, Non-U.S. Gov't
  • Validation Study

MeSH terms

  • Adult
  • Biomarkers / blood
  • Biomarkers / urine
  • C-Peptide / blood
  • C-Peptide / urine*
  • Creatinine / blood
  • Creatinine / urine*
  • Diabetes Mellitus, Type 2 / blood*
  • Diabetes Mellitus, Type 2 / urine*
  • Fasting
  • Female
  • Glomerular Filtration Rate
  • Humans
  • Insulin / metabolism*
  • Insulin Secretion
  • Male
  • Postprandial Period
  • Predictive Value of Tests
  • Reproducibility of Results


  • Biomarkers
  • C-Peptide
  • Insulin
  • Creatinine