Can I use the mat if I have diabetes?

Diabetic patients may use FIR heat but with extra care.

A lot depends on the type of diabetic disease. 

Diabetes is included into contraindication list because some diabetic patients loose sensitive to heat.

It is dangerous for such patients to use the mat because they simply do not feel the heat and may get overheating or low temperature burns.

Start low and go slow. It is the best way to get cumulative effect.