I don't buy into all of the "it's genetic" claims. This excuse is a go-to when the medical profession can't explain something and is mostly due to a bad lifestyle.
The main thing they can't explain is the functions of water and salt in the body. The pharmaceutical companies have an influence on what is taught in medical schools and because water and salt don't fit their agenda, it isn't covered extensively enough.
600 teaching hours are spent learning the effects that pharmaceuticals have on the physiology of the body while only 6 teaching hours are devoted to nutrition (where water and salt would be covered).
Thus, water has little or no importance in the eyes of doctors and salt has been demonized.
Water and salt have a multitude of functions in the body - every function depends on them and they regulate every function. They're also necessary for the production of electrical energy in the body - a process called "hydrolysis". This electrical energy is used as a communications tool between the brain and every part of the body. It's also used to burn calories that produce energy.
When you don't drink enough water and/or don't use enough salt, this energy can't be produced efficiently, so the brain turns to sugar for most of its energy needs. At this point, it is running on almost 100% sugar, so it instructs the liver to keep pumping it out. Recent studies have shown that insulin resistance is linked to dehydration. With blood normally being 94% water, and with dehydration lowering the water volume by 8%, it thickens the blood, which hinders the effectiveness of insulin.
This overwhelms the ability of the pancreas to produce enough insulin, and the result becomes diabetes.
Eating sugar is no more hazardous as eating salt - the key is moderation. But more importantly, you have to keep your body properly hydrated using water and salt. This is the best preventative.