Types of Diabetes
Diabetes is classified depending on the process that leads to increase in the blood glucose level.
Diabetes is as follows:
Type 1 Diabetes is an autoimmune disease in which your body's immune cells identify your own beta cells in the pancreas as “foreign” and attack them. This leads to the destruction of beta cells of pancreas, resulting in an absolute insulin deficiency.
In the absence of insulin, glucose fails to enter the cells thereby increasing the blood sugar levels resulting in a condition known as hyperglycemia. The excess sugar is excreted in the urine. Weakness, weight loss, excessive hunger and thirst are among the few symptoms of diabetes."
Administration of exogenous insulin is essential for the survival of patients with Type 1 Diabetes.
Individuals with Type 1 Diabetes tend to have following characteristics.
- Onset below 30 years of age
- Lean body habitus
- Require insulin from the start of therapy
- Propensity to develop ketoacidosis (one of acute complications of diabetes)
- Most of the individuals with type 1 diabetes do not have first degree relatives with this disorder.
Type 2 diabetes occurs when the body produces enough insulin but cannot utilize it effectively.
It is characterized by three abnormalities
- Insulin Resistance
- Impaired insulin secretion and
- Increased production of glucose from liver
- Insulin Resistance: Inability of insulin to act effectively or inappropriate usage of insulin by the body leads to insulin resistance. This results in rise of blood glucose levels above normal range. As the blood glucose levels rise, the individual develops Prediabetes during which glucose levels (Fasting Plasma Glucose FPG 100 to 125 mg/dL) are slightly elevated. Over a period of time glucose levels increase further thereby converting prediabetes into diabetes. Obesity, sedentary lifestyle, genetic factors and ageing are the risk factors for the insulin resistance.
- Impaired Insulin Secretion: Insulin secretion initially increases in response to insulin resistance. Over a period of time beta cells of pancreas get exhausted. Insulin secreted by the remaining beta cells of pancreas fail to control blood glucose within the normal range resulting in hyperglycemia. Though the exact cause of beta cell death is unknown glucotoxicity (i.e. the toxicity due to increased blood glucose level) remains one of the important causes of beta cell death. Control of blood glucose level thus can improve the function of beta cells.
- Increased production of glucose from the liver: Insulin resistance leads to increased glucose production in the liver that further contributes to an increase in the blood glucose level.
Type 2 diabetes is a progressive disease. At the time of diagnosis approximately 50 % of beta cells of pancreas which secretes insulin are damaged and over a period of time majority of beta cells die. Therefore blood glucose, in diabetic patients, in initial period after diagnosis can be controlled with oral antidiabetic drugs or tablets but during later part of life they require insulin injection for the control of blood glucose level. Your doctor will decide suitable treatment for you. (Ref. UK Prospective Diabetes Group. Diabetes. 1995; 44:1249 -1258)
Individuals with type 2 diabetes tend to have following characteristics.
- Onset after 30 years of age
- Usually obese (80 % are obese but elderly individuals may be lean)
- May not require insulin from the beginning
- May have associated disorder like high blood pressure and altered lipid levels
Type 2 is much more common than Type 1 and accounts for more than 95% of all diabetics. It is the commonest type of diabetes seen in India.
Gestational diabetes is a form of diabetes which affects pregnant women. It is believed that the hormones secreted by the placenta that help the baby develop, block the normal action of insulin in body during pregnancy. This makes it hard for the mother's body to use insulin and thus sugar builds up in the blood to high levels.
Gestational diabetes may affect both the baby and the mother. Baby may develop abnormalities like excessively large sized baby. Also the risk of obesity and development of diabetes increases during later part of life in such a baby.
The American Diabetic Association advises screening for gestational diabetes between weeks 24 to 28 of pregnancy in women with increased risk gestational diabetes. Discuss with your doctor about the risk factors (age > 25 yrs., Obesity, family history of diabetes etc) for gestational diabetes.
Specific types of diabetes due to other causes e.g. genetic defects in β-cell function, defects in insulin action, drug or chemical induced diseases of the pancreas.