High blood sugar levels cause swelling in the lens of the eye, temporarily causing changes in vision.

Insufficient insulin prevents the body from getting glucose from the blood into the body's cells to use as energy. So the body starts burning fat and muscle for energy, causing a reduction in overall body weight.

When your kidneys can't keep up, the excess glucose is excreted into your urine, dragging along fluids from your tissues, which makes you dehydrated.

Due to either a lack of insulin or insulin resistance the body can't convert the food you eat into energy resulting increase in appetite

It is a symptom of hyperglycemia, or high blood sugar.

Due to instability of blood sugar levels