Type 1, which used to be called insulin-dependent diabetes, occurs when the body fails to produce insulin, the hormone required for controlling blood sugar levels. Sufferers require insulin injections to correct this. There is no known dietary cause of type 1 diabetes.
However, for those who have type 1 diabetes, diet is an important part of their clinical care. All type 1 patients should have access to a qualified dietician.

Type 2 diabetes often develops later in life although cases in obese children and young adults are becoming more common. This type of diabetes is usually associated with being overweight. In this case, too much insulin is produced by the body but it still has little or no effect on blood sugar.
This type can often be treated with diet alone, although in the later stages of the disease insulin production may decline and

some people will need tablets or insulin injections. The risk of type 2 diabetes rises as body fat increases. If you're an obese man, your risk of developing diabetes is 40 times higher than if you are a healthy weight. This risk more than doubles in obese women.
You can reduce your risk of developing type 2 diabetes by achieving and maintaining a healthy weight. It's worth noting that despite diabetes being a condition of sugar regulation, specific restriction of sugars isn't necessary, except as part of ensuring a balanced diet overall.