What number is low blood sugar for a diabetic? That depends on the age of the diabetic and the type of diabetes that he or she has. According to the International Diabetes Federation:. A child with diabetes should have a blood glucose level ranging from 4 to 8 mmol/L. Adults with type 1 or type 2 diabetes should have a blood glucose level ranging from 4 to 7 mmol/L. However, a diabetic's glucose level will always rise right after eating. A child with diabetes may have a blood glucose level of up to 10 mmol/L.…