Type 2 diabetes is usually associated with being overweight (BMI greater than 25), and is harder to control when food choices are not adjusted, and you get no physical activity. And while it’s true that too much body fat and physical inactivity (being sedentary) does increase the likelihood of developing type 2, even people who are fit and trim can develop this type of diabetes.2,3
Diet, exercise, and education are the cornerstones of treatment of diabetes and often the first recommendations for people with mild diabetes. Weight loss is important for people who are overweight. People who continue to have elevated blood glucose levels despite lifestyle changes, or have very high blood glucose levels and people with type 1 diabetes (no matter their blood glucose levels) also require drugs.
Complications of diabetes are responsible for considerable morbidity and mortality. The acute complications of diabetes are hypo- and hyperglycemic coma and infections. The chronic complications include microvascular complications such as retinopathy and nephropathy, and the macrovascular complications of heart disease and stroke. Diabetes mellitus is the commonest cause of blindness and renal failure in the UK and the USA. Other common complications include autonomic and peripheral neuropathy. A combination of vascular and neuropathic disturbances results in a high prevalence of impotence in men with diabetes. Peripheral neuropathy causes lack of sensation in the feet which can cause minor injuries to go unnoticed, become infected and, with circulatory problems obstructing healing, ulceration and gangrene are serious risks and amputation is not uncommon. Evidence from meta-analysis of studies of the relationship between glycemic control and microvascular complications (Wang, Lau, & Chalmers, 1993), and from the longitudinal multicenter Diabetes Control and Complications Trial (DCCT) in the USA (DCCT Research Group, 1993), have established a clear relationship between improved blood glucose control and reduction of risk of retinopathy and other microvascular complications in insulin-dependent diabetes mellitus (IDDM). It is likely that there would be similar findings for noninsulin-dependent diabetes mellitus (NIDDM) though the studies did not include NIDDM patients. However, the DCCT included highly selected, well-motivated, well-educated and well-supported patients, cared for by well-staffed diabetes care teams involving educators and psychologists as well as diabetologists and diabetes specialist nurses.

Intensive blood sugar lowering (HbA1c<6%) as opposed to standard blood sugar lowering (HbA1c of 7–7.9%) does not appear to change mortality.[74][75] The goal of treatment is typically an HbA1c of 7 to 8% or a fasting glucose of less than 7.2 mmol/L (130 mg/dl); however these goals may be changed after professional clinical consultation, taking into account particular risks of hypoglycemia and life expectancy.[59][76][77] Despite guidelines recommending that intensive blood sugar control be based on balancing immediate harms with long-term benefits, many people – for example people with a life expectancy of less than nine years who will not benefit, are over-treated.[78]

This depends on the type of diabetes. Type 2 diabetes, and to a lesser extent type 1 diabetes, may run in families. If a parent has diabetes, their children will not necessarily get it but they are at an increased risk. In type 2 diabetes, lifestyle factors such as being overweight (obesity) and lack of exercise can significantly increase your risk of developing diabetes. Some rarer types of diabetes mellitus may be inherited.
The classic presenting symptoms of type 1 diabetes mellitus are discussed below. For some children, the first symptoms of diabetes mellitus are those of diabetic ketoacidosis. This is a serious and life-threatening condition, requiring immediate treatment. Ketoacidosis occurs due to a severe disturbance in the body’s metabolism. Without insulin, glucose cannot be taken up into cells. Instead fats are broken down for energy which can have acid by-products.  
Diabetes mellitus is a chronic disease for which there is treatment but no known cure.  Treatment is aimed at keeping blood glucose levels as close to normal as possible.  This is achieved with a combination of diet, exercise and insulin or oral medication.  People with type 1 diabetes need to be hospitalized right after they are diagnosed to get their glucose levels down to an acceptable level.
High blood glucose sets up a domino effect of sorts within your body. High blood sugar leads to increased production of urine and the need to urinate more often. Frequent urination causes you to lose a lot of fluid and become dehydrated. Consequently, you develop a dry mouth and feel thirsty more often. If you notice that you are drinking more than usual, or that your mouth often feels dry and you feel thirsty more often, these could be signs of type 2 diabetes.