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Validation of a single‐sample urinary C‐peptide creatinine ratio as a reproducible alternative to serum C‐peptide in patients with Type 2 diabetes
Author(s) -
Bowman P.,
McDonald T. J.,
Shields B. M.,
Knight B. A.,
Hattersley A. T.
Publication year - 2012
Publication title -
diabetic medicine
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.474
H-Index - 145
eISSN - 1464-5491
pISSN - 0742-3071
DOI - 10.1111/j.1464-5491.2011.03428.x
Subject(s) - c peptide , creatinine , medicine , renal function , urine , endocrinology , postprandial , diabetes mellitus , type 2 diabetes , urology
Diabet. Med. 29, 90–93 (2012) Abstract 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.