VDAC1 and diabetes mellitus: Of note, we found that verapamil treatment downregulated protein expression of both VDAC isoforms (VDAC1/2); considering that VDAC1 was upregulated by a state of glucotoxicity over a prolonged period in pre-diabetic patients [53,54,55], verapamil could be an ideal therapy to prevent both the development and progression of diabetes.