** Thanks for contacting HCM with your health concern 1. Since you are suffering from diabetes and hypertension thus first check with a Medicine Specialist to exclude K-W- Syndrome [kimmelstiel wilson] and increasing dose of insulin despite diet restriction suggests poor blood sugar control which needs immediate Endocrinologist intervention 2. Since magnesium is required for the regulation of blood pressure and insulin metabolism thus deficiency of same [hypomagnesemia] can result in insulin resistance,hypertension and cardiovascular disease thus check with your attending physician to know about the dosage and form [oral/ intravenous] which is best suited for you.