Blood C-peptide,first-void fasting urinary C-peptide/creatinine ratio ( UCPCR ),second-void fasting UCPCR,and 24 h urinary C-peptide (UCP) were determined in 90 type 2 diabetics and 30 health volunteers.The results showed that first-void fasting UCPCR and second-void fasting UCPCR were positively related to 24 h UCP and the index of islet β-cell function( all P<0.01 ).