Previous studies reported that stability of insulin was better on ethylenediaminetetraacetic acid (EDTA) plasma sample than serum sample. However, those studies used tripotassium EDTA (K3-EDTA) tubes, rather than dipotassium EDTA (K2-EDTA) tubes which are more commonly used in laboratories. We investigated the impact of preservative type of EDTA (K2 or K3) on the stability of C-peptide and insulin at 4°C and at room temperature room. Our study has identified that K2-EDTA achieves longer stability of insulin but does not improve the stability of C-peptide. Insulin and C-peptide are stable 24h on the same K2-EDTA sample at room temperature.
Keywords: C-peptide; EDTA; Haemolysis; Insulin; Stability.
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