The main characteristic of diabetes mellitus is that the body loses the ability to lower blood glucose levels down to acceptable levels. Usually the body produces sufficient insulin to help control excess glucose so that the liver and muscles can convert and store excess glucose as glycogen. However with diabetics the body either can't lower glucose levels sufficiently or deal with the insulin in the bloodstream.

Type 1 Diabetes - If the insulin levels are usually too low then it's likely that Type 1 diabetes will develop. Type 1 diabetes is also known as insulin dependent or juvenile onset diabetes. Type 1 diabetes requires the regular use of insulin to maintain blood glucose levels. Type 1 diabetes usually affects children and young adults.

Type 2 Diabetes - This type of diabetes mellitus is much more common and more likely to affect adults over 30 years old. Quite often type 2 diabetes can be triggered by inadequate exercise combined with a bad diet.