BCL2 and diabetes mellitus: Prevents the atrophy of myeloid axons and reduces the expression of inflammatory mediators; restores the shape of the sciatic nerve; alleviates mechanical hyperalgesia, thermal hyperalgesia, and abnormal cold pain caused by diabetes; downregulates the pro-apoptotic protein caspase 3 and Bax of the dorsal root ganglion; upregulates the level of anti-apoptotic protein Bcl-2