A correlation association was found between increases in serum calcitonin and duration of diabetes (R = 0.638; p=0.001) for T1DM and for T2DM (R = 0.430, p=0.001).A positive linear relationship was established between the level of CT and the HOMA-IR index with increased duration of T2DM (R = 0.615; p=0.03); thus, confirming previous studies, which detected that calcitonin inhibits glucose-stimulated insulin release. Here, CALCA is linked to type 2 diabetes mellitus.