Weight fluctuations also fall under the umbrella of possible diabetes signs and symptoms. When you lose sugar through frequent urination, you also lose calories. At the same time, diabetes may keep the sugar from your food from reaching your cells — leading to constant hunger. The combined effect is potentially rapid weight loss, especially if you have type 1 diabetes.
The genes identified so far in people with type 2 include many that affect the insulin-producing beta cells of the pancreas, says Craig Hanis, PhD, a professor at the Human Genetics Center at the University of Texas Health Science Center in Houston. And yet he emphasizes that why people get type 2 isn't at all clear yet: "What it tells us is that diabetes is a complicated disease."

Type 2 diabetes primarily occurs as a result of obesity and lack of exercise.[1] Some people are more genetically at risk than others.[6] Type 2 diabetes makes up about 90% of cases of diabetes, with the other 10% due primarily to diabetes mellitus type 1 and gestational diabetes.[1] In diabetes mellitus type 1 there is a lower total level of insulin to control blood glucose, due to an autoimmune induced loss of insulin-producing beta cells in the pancreas.[12][13] Diagnosis of diabetes is by blood tests such as fasting plasma glucose, oral glucose tolerance test, or glycated hemoglobin (A1C).[3]

People with full-blown type 2 diabetes are not able to use the hormone insulin properly, and have what’s called insulin resistance. Insulin is necessary for glucose, or sugar, to get from your blood into your cells to be used for energy. When there is not enough insulin — or when the hormone doesn’t function as it should — glucose accumulates in the blood instead of being used by the cells. This sugar accumulation may lead to the aforementioned complications.