It's important to know that not all cases of diabetes will show diabetes symptoms unless the diabetes is severe. Others will have early symptoms that can be picked up if one is vigilant. For example, one symptom of early diabetes is that of episodes of "low blood sugar", also called hypoglycemia. With this symptom, a person will experience shakiness, sweating, hunger pangs and dizziness because the insulin has overshot the target blood sugar.

Those with diabetes symptoms related to very high blood sugar often feel a general sense of illness, weight loss and nausea. They can also feel dizzy or light-headed. When these symptoms occur, the blood sugar is often greater than 300 mg per deciliter but can be as high as 600 milligrams per deciliter. Blood sugars above 600 milligrams per deciliter can cause an altered sense of consciousness and a diabetic coma.

Those with Type I diabetes have slightly different diabetes symptoms. These individuals have some of the same symptoms of Type II diabetes but can get into much more severe symptoms such as diabetic ketoacidosis. This occurs when byproducts of metabolism, called ketones, build up in the body. This causes stomach pains, generalized loss of consciousness and coma, which can be fatal. Type I diabetics can also have symptoms of low blood sugar if they take too much insulin.

Diabetics can develop diabetic symptoms, even if they are in moderate control. Diabetics carry a risk of losing nerve function to the nerves of the legs, a condition called peripheral neuropathy. This results in the inability to feel things with one's feet. Diabetic foot ulcers can develop as a result of poor nerve and circulatory function.

Diabetics can develop the diabetic symptom of poor vision. This is because untreated diabetes causes changes in the blood vessels in the eyes so that the vision becomes poor. The condition is called diabetic retinopathy and can be treated by using laser treatments to the retina.

Kidney disease is another diabetic symptom. This generally happens when the diabetes is poorly treated. There may or may not be actual symptoms, like water retention, but tests will show that the kidneys are failing. This can lead to needing a kidney transplant or dialysis if the symptoms are severe.

The cardiovascular system can play a role in diabetes. Peripheral vascular disease, or poor circulation to the legs, is a diabetic symptom. This can result in cold feet or foot ulcers in diabetics. The heart can also be involved. Diabetes is a risk factor for having a heart attack. This is the biggest reason why early and careful control is important for diabetics at all stages of the disease. In fact, most of the complications of diabetes can be improved by improving the various diabetic symptoms early.