Objective: To explore the possibility of miR-374b as a potential diagnostic indicator of type 2 diabetes mellitus (T2DM) and the potential molecular mechanism of miR-374b in the pathogenesis of T2DM. Methods: Serum miR-374b expression level of 30 T2DM patients and 30 healthy controls was detected by qRT-PCR, biochemical analyzer was used to determine relevant biochemical indicators, and the auxiliary diagnostic value of serum miR-374b in the two groups was analyzed by logistic regression. Moreover, by transfecting miR-374b mimics into the pancreatic β-cell MIN-6, the effect of miR-374b mRNA levels on pro-apoptotic gene Bax and anti-apoptotic gene bcl-2 was detected by qRT-PCR. Results: qRT-PCR analysis showed that the serum miR-374b expression level in the T2DM patients was significantly higher than that of the healthy control group (P<0.01). Further logistic regression analysis showed that the serum miR-374b expression level was an independent risk factor for T2DM.Cell experiments showed that miR-374b significantly promoted the expression of pro-apoptotic gene Bax mRNA and inhibited the mRNA expression of anti-apoptotic gene bcl-2. Conclusion: The high expression of miR-374b in serum is a potential non-invasive auxiliary diagnostic marker and an independent risk factor for T2DM patients. Increased expression of miR-374b leads to apoptosis of islet β-cell.