C-peptide and insulin assays with the Mindray CL-2000i: Precision and comparability with different methods

C-peptide and insulin are widely used in clinical practice for the diagnosis for several conditions, including hypoglycaemia and diabetes. However, the lack of method harmonization represents an important analytical limitation. Aims of this study were to evaluate new Mindray CL-2000i C-peptide and insulin methods for precision and comparability with Tosoh AIA-CL2400 and Siemens Immulite 2000 systems.

Mindray CL-2000i precision was evaluated by the CLSI EP15-A3 protocol and compared with the manufacturer's claimed values. A series of one hundred sixty-five specimens were used for comparing C-peptide and immunoreactive insulin (IRI) between Mindray CL-2000i, Tosoh AIA-CL2400 and Siemens Immulite 2000.

Mindray CL-2000i repeatability results were 1.7% and 1.35% for C-peptide and 2.1% and 1.2% for IRI. Intermediate precisions were 2.6% and 1.4% for C-peptide and 4.6% and 2.3% for IRI. For C-peptide, Mindray CL-2000i performed similarly to Tosoh AIA-CL2400; for IRI a good agreement between Mindray C-2001 and Siemens Immulite 2000was found.

Mindray CL-2000i shows a low imprecision while a satisfactory for IRI between Mindray 2000i and Siemens Immulite 2000 was onbserved. Overall, results emphasize the need for standardization/harmonization efforts for both C-peptide and IRI measurement.