The word mellitus (/məˈlaɪtəs/ or /ˈmɛlɪtəs/) comes from the classical Latin word mellītus, meaning "mellite"[117] (i.e. sweetened with honey;[117] honey-sweet[118]). The Latin word comes from mell-, which comes from mel, meaning "honey";[117][118] sweetness;[118] pleasant thing,[118] and the suffix -ītus,[117] whose meaning is the same as that of the English suffix "-ite".[119] It was Thomas Willis who in 1675 added "mellitus" to the word "diabetes" as a designation for the disease, when he noticed the urine of a diabetic had a sweet taste (glycosuria). This sweet taste had been noticed in urine by the ancient Greeks, Chinese, Egyptians, Indians, and Persians.
A. Diabetes is the inability of the body to ‘produce insulin - type 1 diabetes’ or ‘proper use of insulin - type 2 diabetes, gestational diabetes and pre-diabetes’. Diabetes is often goes undiagnosed because many of the symptoms of diabetes seems harmless. The causes of diabetes continues to be a mystery, pancreas it the organ whose defect causes diabetes.
nephrogenic diabetes insipidus a rare form caused by failure of the renal tubules to reabsorb water; there is excessive production of antidiuretic hormone but the tubules fail to respond to it. Characteristics include polyuria, extreme thirst, growth retardation, and developmental delay. The condition does not respond to exogenous vasopressin. It may be inherited as an X-linked trait or be acquired as a result of drug therapy or systemic disease.

"Brittle" diabetes, also known as unstable diabetes or labile diabetes, is a term that was traditionally used to describe the dramatic and recurrent swings in glucose levels, often occurring for no apparent reason in insulin-dependent diabetes. This term, however, has no biologic basis and should not be used.[40] Still, type 1 diabetes can be accompanied by irregular and unpredictable high blood sugar levels, frequently with ketosis, and sometimes with serious low blood sugar levels. Other complications include an impaired counterregulatory response to low blood sugar, infection, gastroparesis (which leads to erratic absorption of dietary carbohydrates), and endocrinopathies (e.g., Addison's disease).[40] These phenomena are believed to occur no more frequently than in 1% to 2% of persons with type 1 diabetes.[41]
Type 1 diabetes is characterized by loss of the insulin-producing beta cells of the pancreatic islets, leading to insulin deficiency. This type can be further classified as immune-mediated or idiopathic. The majority of type 1 diabetes is of the immune-mediated nature, in which a T cell-mediated autoimmune attack leads to the loss of beta cells and thus insulin.[38] It causes approximately 10% of diabetes mellitus cases in North America and Europe. Most affected people are otherwise healthy and of a healthy weight when onset occurs. Sensitivity and responsiveness to insulin are usually normal, especially in the early stages. Although it has been called "juvenile diabetes" due to the frequent onset in children, the majority of individuals living with type 1 diabetes are now adults.[39]
Keeping track of the number of calories provided by different foods can become complicated, so patients usually are advised to consult a nutritionist or dietitian. An individualized, easy to manage diet plan can be set up for each patient. Both the American Diabetes Association and the American Dietetic Association recommend diets based on the use of food exchange lists. Each food exchange contains a known amount of calories in the form of protein, fat, or carbohydrate. A patient's diet plan will consist of a certain number of exchanges from each food category (meat or protein, fruits, breads and starches, vegetables, and fats) to be eaten at meal times and as snacks. Patients have flexibility in choosing which foods they eat as long as they stick with the number of exchanges prescribed.
About Diabetes, Type 2:  Type 2 diabetes is characterized by "insulin resistance" as body cells do not respond appropriately when insulin is present. This is a more complex problem than type 1, but is sometimes easier to treat, since insulin is still produced, especially in the initial years. Type 2 may go unnoticed for years in a patient before diagnosis, since the symptoms are typically milder (no ketoacidosis) and can be sporadic. However, severe complications can result from unnoticed type 2 diabetes, including renal failure, and coronary artery disease. Type 2 diabetes was formerly known by a variety of partially misleading names, including "adult-onset diabetes", "obesity-related diabetes", "insulin-resistant diabetes", or "non-insulin-dependent diabetes" (NIDDM). It may be caused by a number of diseases, such as hemochromatosis and polycystic ovary syndrome, and can also be caused by certain types of medications (e.g. long-term steroid use). About 90-95% of all North American cases of diabetes are type 2, and about 20% of the population over the age of 65 is a type 2 diabetic. The fraction of type 2 diabetics in other parts of the world varies substantially, almost certainly for environmental and lifestyle reasons. There is also a strong inheritable genetic connection in type 2 diabetes: having relatives (especially first degree) with type 2 is a considerable risk factor for developing type 2 diabetes. The majority of patients with type 2 diabetes mellitus are obese - chronic obesity leads to increased insulin resistance that can develop into diabetes, most likely because adipose tissue is a (recently identified) source of chemical signals (hormones and cytokines).
A. Diabetes is the inability of the body to ‘produce insulin - type 1 diabetes’ or ‘proper use of insulin - type 2 diabetes, gestational diabetes and pre-diabetes’. Diabetes is often goes undiagnosed because many of the symptoms of diabetes seems harmless. The causes of diabetes continues to be a mystery, pancreas it the organ whose defect causes diabetes. 

Persons with diabetes who take insulin must be careful about indulging in unplanned exercise. Strenuous physical activity can rapidly lower their blood sugar and precipitate a hypoglycemic reaction. For a person whose blood glucose level is over 250 mg/dl, the advice would be not to exercise at all. At this range, the levels of insulin are too low and the body would have difficulty transporting glucose into exercising muscles. The result of exercise would be a rise in blood glucose levels.
Your body uses a system of organs and hormone signals to regulate body fluids. The kidneys play an important role in this fluid regulation by removing extra fluid from your bloodstream. The bladder stores this fluid waste until you urinate it out. Your body regulates fluid levels by making less urine when you need to replace fluid lost to sweating, or by making more urine when there is too much fluid in your body.
Some people who have type 2 diabetes can achieve their target blood sugar levels with diet and exercise alone, but many also need diabetes medications or insulin therapy. The decision about which medications are best depends on many factors, including your blood sugar level and any other health problems you have. Your doctor might combine drugs from different classes to help you control your blood sugar in several different ways.
Persons with diabetes are prone to infection, delayed healing, and vascular disease. The ease with which poorly controlled diabetic persons develop an infection is thought to be due in part to decreased chemotaxis of leukocytes, abnormal phagocyte function, and diminished blood supply because of atherosclerotic changes in the blood vessels. An impaired blood supply means a deficit in the protective defensive cells transported in the blood. Excessive glucose allows organisms to grow out of control.
Central diabetes insipidus. A synthetic, or man-made, hormone called desmopressin treats central diabetes insipidus. The medication comes as an injection, a nasal spray, or a pill. The medication works by replacing the vasopressin that a patient’s body normally produces. This treatment helps a patient manage symptoms of central diabetes insipidus; however, it does not cure the disease.