What health problems can my child's diabetes mellitus type 2 cause?

Many. This is "metabolic syndrome" and indicates Insulin resistance. That means that he has a high blood Insulin that does not do its job properly. The common cause is bad diet. Take all the "junk" away, particularly all the sugar, sweeteners, pop, ice cream, candies etc. The overall health of an individual with this is awful and you can expect complications.
Rapid CardioVascular. Atherosclerosis leading to heart attack, peripheral artery disease (loss of toes, feet, legs), neuropathy, stroke, etc., along with kidney failure & blindness are principle consequences; quite accelerated in those with dm. Typically little done until symptoms severe, too late. Thus ?sugar/carbs, ?body fat, ?activity, optimize NMR lipoproteins, get hba1c ?6.0% at min (?5.0% optimal) & sbp ?120 mmhg.
DM 2. Dm 2 acute symptoms- diabetic ketoacidosis, hyperosmolar state, hypoglycemic episodes chronic effects- due to atherosclerosis, coronary artery diseases, peripheral vascular disease, adiposity, hyper triglyceredemia, kidney failure, retinopathy etc.

Related Questions

What other health problems can diabetes mellitus type 1 cause you?

Many. Blindness, heart disease, hardening of the arteries, renal failure, amputations to name a few. Most accelerated by poor control. Read more...
See below. Uncontrolled diabetes can lead to heart disease, heart attack, stroke, kidney disease/failure, peripheral vascular disease, numbness in legs, increased risk of infection, amputations of limbs, gastroparesis, impotence (new made-up term by the drug companies is erectile dysfunction), depression, liver disease. Read more...