a decreasing trendP =0.0059
The intra-laboratory %CVs presented a decreasing trend with increasing insulin concentration (ANOVA: P =0.0059; 202111 vs. 202113 P =0.0255; 202111 vs. 202115 P =0.0063); however, no distinct trend was observed for C-peptide (ANOVA: P =0.702) ( Fig. 1 ).