Bitter melon is a member of the squash family and looks like a cucumber with very bumpy skin. They are fat free, saturated fat free, cholesterol free, sodium free, and an excellent source of vitamin C.
Compounds present in bitter melon have been studied for their antidiabetic properties. Due to the various available preparations, e.g. extract, capsules, and powder, various doses are available and raise concerns over possible complications such a low blood sugar and liver toxicity because there is no standard treatment or dose. I recommend your son follow-up with his physician to review his current diabetes regimen including the use of bitter melon for safe measure.