So far, we have learned that Diabetes Mellitus is a chronic disease in which the human body is not able to produce or properly use insulin. Insulin is a hormone that converts food, sugars and starches to energy. Both genetic and environmental factors such as obesity, poor diet, and lack of exercise contribute to diabetes incidence.
Most commonly, Diabetes mellitus (DM) is divided into the following classifications:

Type 1 Diabetes:

The most serious form of diabetes, it is also called Insulin Dependent Diabetes Mellitus (IDDM). It results from failure of body to produce insulin because the immune system which normally fights harmful bacteria and viruses has attacked and destroyed the insulin producing cells of the pancreas.
Type 1 diabetes is characterized by total destruction of the insulin-producing beta cells, probably by an autoimmune reaction. Onset is most common in childhood, thus the common (but now deprecated) term “juvenile-onset”, but the onset up to age 40 is not uncommon and can even occur later. Patients are susceptible to DKA (diabetic ketoacidosis). There seems to be some genetic tendency, but the genetic situation is unclear. Most patients are lean. Always requires treatment by insulin. Not sex-linked. Also referred to as IDDM (insulin dependent diabetes mellitus). Although IDDMcan develop at any stage, it most commonly appears in children, adolescents and young adults.
According to CDC (Center for Disease Control) one in every 400 to 600 adolescents in the U.S. has or will have type 1 diabetes.

Type 2 Diabetes:

This is the most common form, and is also referred as Non-Insulin Dependent Diabetes Mellitus (NIDDM). In this form of diabetes either the pancreas cannot produce enough insulin or the body cannot effectively use insulin. NIDDM occurs in people over 40, and it usually develops as a result of genetic disposition combined with obesity and a sedentary lifestyle. Despite the fact that patients do not require insulin in the early stages of the disease and can be treated with oral medication, self monitoring of blood glucose (SMBG) is required for good control of the disease.
Type 2 diabetes is characterized by insulin resistance despite adequate insulin production. A large majority of patients are overweight at onset, and a majority is female. Most are over 40, hence the common (but now deprecated) terms “adult-onset” or “maturity-onset”, but onset can occur at any age. Patients are not susceptible to DKA (diabetic ketoacidosis). There is a strong genetic tendency, but not simple inheritance. Depending on the individual, treatment may be by diet, exercise, weight loss, oral drugs which stimulate the release of insulin, or insulin injections — and usually a combination of several of these.

Gestational Diabetes:

This form of diabetes occurs in approximately 3% of all pregnancies as a result of insulin antagonists secreted by the placenta. It is recommended that all pregnant women receive a screening glucose tolerance test (GTT) between the 24th and 28th weeks of pregnancy to detect gestational diabetes early if it occurs, as diabetes can cause serious difficulties in pregnancy. Sometimes requires insulin treatment. Not susceptible to DKA (diabetic ketoacidosis). Usually disappears after childbirth, but about 40% of patients develop type 2 diabetes within five years. Most authorities state that the typical patient is female.

Pre-Diabetes:

Pre-diabetes refers to blood glucose levels that are higher than normal, but not yet high enough to be diagnosed as type 2 diabetes (i.e. a fasting plasma glucose level of 7.0 mmol/L or higher). Although not everyone with pre-diabetes will develop type 2 diabetes, many people will. t is important to know if you have pre-diabetes, because research has shown that some long-term complications associated with diabetes – such as heart disease and nerve damage – may begin during pre-diabetes. This form of diabetes occurs in approximately 3% of all pregnancies as a result of insulin antagonists secreted by the placenta.

Malnutrition-related Diabetes:

This rarely researched type of diabetes is caused by severe malnutrition – severe malnutrition sometimes can cause hyperglycemia and all the usual symptoms. The reason is unknown, and since this syndrome occurs almost entirely in third world countries, research on this form of diabetes is nearly nonexistent.

Diabetes Insipidus:

Diabetes insipidus (DI) results from abnormalities in the production or use (two main types) of the hormone arginine vasopressin. The main symptoms are excessive thirst and massive urination. The excess urine flow is devoid of sugar. There are no blood glucose abnormalities, and in fact there is nothing in common with diabetes mellitus except the excess urination when untreated.
Diabetes insipidus can be caused by failure to produce vasopressin. This is known as neurogenic DI (or central DI, or pituitary DI). It can be treated with hormone replacement (by nasal spray or other routes). DI caused by failure to use vasopressin (nephrogenic DI) is more difficult to treat, but several drugs are available which help. DI is much less common than diabetes mellitus. The number of DI patients is only 1 or 2 per 10,000 population (25,000-50,000 in the US).

Other Types of Diabetes:

A number of other types of diabetes exist. A person may exhibit characteristics of more than one type. For example, in latent autoimmune diabetes in adults (LADA), also called type 1.5 diabetes or double diabetes, people show signs of both type 1 and type 2 diabetes. Diagnosis usually occurs after age 30.
Most people with LADA still produce their own insulin when first diagnosed, like those with type 2 diabetes, but within a few years, they must take insulin to control blood glucose levels. In LADA, as in type 1 diabetes, the beta cells of the pancreas stop making insulin because the body’s immune system attacks and destroys them. Some experts believe that LADA is a slowly developing kind of type 1 diabetes.

Other types of diabetes include those caused by:

  • genetic defects of the beta cell, such as maturity-onset diabetes of the young (MODY) and neonatal diabetes mellitus
  • genetic defects in insulin action, resulting in the body’s inability to control blood glucose levels, as seen in leprechaunism and the Rabson-Mendenhall syndrome
  • diseases of the pancreas or conditions that damage the pancreas, such as pancreatitis and cystic fibrosis
  • excess amounts of certain hormones resulting from some medical conditions—such as cortisol in Cushing’s syndrome—that work against the action of insulin
  • medications that reduce insulin action, such as glucocorticoids, or chemicals that destroy beta cells
  • infections, such as congenital rubella and cytomegalovirus
  • rare autoimmune disorders, such as stiff-man syndrome, an autoimmune disease of the central nervous system
  • genetic syndromes associated with diabetes, such as Down syndrome and Prader-Willi syndrome

Factoid:

The CDC and American Diabetes Association (ADA) have estimated that 25M people, or 8% of the population, have diabetes in the US. Almost 1/3 (approximately 8M people) are unaware that they have it. An additional 41M people have pre-diabetes (glucose intolerance). The U.S. spends approximately $558.3M USD on in-vitro diabetes testing (Frost &Sullivan Report).