[stevewoods]

High Sugar Intake Leads to Diabetes?
Your first question is actually a very common misconception amongst people. A high caloric diet is not a trigger to diabetes in a non-diabetic person. There are actually two types of diabetes (Type 1 and Type 2), whereas type-1 diabetes is more related to genetic factors, type-2 is influenced by lifestyle (as well). Now, as per established researches, Obese people are more prone to type-2 diabetes, so on those lines one 'can' speculate that a high caloric diet may slowly lead to obesity and eventually "type-2" diabetes. But, a high caloric diet can't lead to type-1 or type-2 diabetes (definitely never type-1) instantly/in short duration.

Control over Sugar Intake can cure a diabetic?
Whereas diet control does help in controlling the blood sugar levels, "one should not STOP" taking calories! It's very common for diabetic people to get "Hypoglycemia shock" due to in-adequate sugar intake. But yes, excess sugars if controlled do help a diabetic person, but they still need insulin (if not insulin resistant diabetes) to manage the blood sugar. Diet control coupled with exercise is best way to curtail Type-2 diabetes.

Diabetes in Children
Diabetes in Children is solely a result of "genetic factors". It's Type-1 diabetes, so it's genetic!