Before making any changes in diet or supplements, be sure to consult with your health professional.
Cramps, numbness and pain in the feet are common when diabetes is not well controlled. Chronic high blood sugar levels can cause nerve damage in the feet which is called diabetic neuropathy. This neuropathy is probably not reversible, which makes it very important that you make a concerted effort to control your blood glucose levels.
In addition, with advanced neuropathy, injuries to the foot may become easily infected because you may not notice them (nerve damage keeps you from feeling pain) and blood flow is impeded by the diabetes slowing down normal recovery. So, the best solution to this problem is to control your blood glucose levels with diet, medication or both.
It is also very important to get regular exercise, which helps to control blood sugar levels as well as to improve or maintain circulation in your feet.
There are several vitamins that can help reduce or prevent this problem, especially B6, B12 and biotin, so if you are diabetic, it's a good idea to take a high potency B vitamin supplement. It is also important to take a natural form of vitamin C daily to help with healing and to prevent infections. Here's more information about nutritional supplements for diabetics.http://www.diabetes-guide.org/nutritional-supplements.htm
In addition, cramps in the feet and legs are sometimes caused by low blood calcium levels. If you decide to take a calcium supplement to help reduce foot cramps, try calcium citrate, which is a much more easily absorbed form than calcium carbonate (which is cheap and common in many supplements). Lack of enough magnesium, another mineral that works in tandem with calcium, may also be the problem. It's best to get a combination supplement that includes both these minerals. In addition you might want to get a supplement that includes a natural form of vitamin D.