First Glance

Fundamentals

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The main features of this classification are as follows :

The terms insulin dependent diabetes mellitus (IDDM) and non-insulin dependent diabetes mellitus (NIDDM) have been dropped, while the terms type 1 and type 2 diabetes mellitus have been retained. The terms IDDM and NIDDM represent a classification based on treatment rather than etiology and present a confusing picture to primary care physicians who do not understand the need and/ or importance of treating NIDDM patients with insulin.

Type 1 diabetes encompasses the vast majority of cases that are primarily due to pancreatic beta cell destruction and are prone to ketoacidosis. Type 1 diabetes is due to lack of insulin. The cause for this type of diabetes may be an autoimmune process. Beta cells of the pancreas are destroyed by the body's own defense mechanism. Most often the person with type 1 diabetes is young and the onset is fairly rapid perhaps over a few days or weeks. However some older people can also get type 1 diabetes.

Type 1 Diabetic individuals tend to be at or below their ideal body weight at diagnosis and may even lose more weight rapidly. They often have ketonemia and ketonuria suggestive of a true insulin lack and burning of fat for energy.

Some patients particularly children and adolescents, may present with ketocidosis as the first manifestation of the disease.

Individuals with Type 1 diabetes become dependent on exogenous insulin for survival and are at risk for ketoacidosis.

Type 2 diabetes NIDDM or adult onset diabetes characterized by the combination of insulin resistance and deficient secretion of insulin. This insulin lack can be caused by a reduced number of insulin producing beta cells. Insulin resistance occurs when the normal interaction between insulin and the insulin receptors on the cells of the body is less effective and glucose is unable to enter the cells. Mainly seen in obese patients, this category represents the majority of diabetes patients who are seen in everyday practice by physicians. Over 80% of people with diabetes suffer from type 2 diabetes⁴.

Type2 diabetes frequently goes undiagnosed for many ears because hyperglycemia develops gradually and at earlier stages is often not severe enough for the patient to notice any of the classical symptoms of diabetes. This type of diabetes has a strong genetic predisposition, typically has its onset later in life cover age 40, and many patients are above their ideal body weight.

Type 2 diabetes in children or adolescents is called "maturity onset diabetes of young (MODY)".

The risk of developing type 2 diabetes increases with

Age
Obesity
Lack of physical activity
Family history diabetes
Genetic predisposition
Women with prior gestational diabetes mellitus
Individuals with hypertension or dyslipidemia

Table 2
Comparison Type 1 and Type 2 Diabetes⁴
	TYPE 1 DIABETES	TYPE 2 DIABETES
Percentage of all people with diabetes	Insulin-dependent diabetes Juvenile diabetes Brittle diabetes	Non-insulin-dependent diabetes Maturity-onset diabetes
Former names	Insulin-dependent diabetes Juvenile diabetes Brittle diabetes	Non-insulin-dependent diabetes Maturity-onset diabetes
Usual age at diagnosis	Usually below 40	Usually over 40 but not always
Condition when discovered	Usually moderately to severely ill	Often not ill at all or having mild symptoms
Aetiology	Reduced or absent insulin production	Insulin resistance and relative deficiency of insulin
Body Weight	Often thin or normal weight. Often losing weight at diagnosis	Usually overweight, but 20% are normal weight
Acute complications	Ketoacidosis	Nonketoic hyperosmolar hyperglycemic coma; not usually prone to ketoacidosis
Usual treatment	Insulin, diet and exercise	Diet, exercise. If needed oral agents, insulin

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