Type 1 Diabetes
Type 2 Diabetes
Other Specific Types of Diabetes
- Genetic defect of beta cell dysfunction
- Genetic defects in insulin action
- Diseases of exocrine pancreas
- Drugs or Chemical induced
- Uncommon forms of immune-medicated diabetes
Stage before Diabetes:
Impaired Glucose Tolerance
Impaired Fasting Glucose
Combined Glucose Intolerance
Type 1 Diabetes
In persons with type 1 diabetes, the beta cells of the pancreas, which are responsible for insulin production, are attacked by the misdirected immune system. It is believed that the tendency to develop abnormal antibodies in type 1 diabetes is, in part, genetically inherited, though the details are not fully understood.
Type 1 diabetes tends to occur in young, lean individuals, usually before 30 years of age; however, older patients do present with this form of diabetes on occasion. This subgroup is referred to as latent autoimmune diabetes in adults (LADA). LADA is a slow, progressive form of type 1 diabetes.
Type 2 Diabetes
In type 2 diabetes, patients can still produce insulin, but due to prevalent insulin resistance, it is inadequate for their body's needs. In many cases this actually means the pancreas produces larger than normal quantities of insulin. A major feature of type 2 diabetes is a lack of sensitivity to insulin by the cells of the body.
In addition to the problems with an increase in insulin resistance, the release of insulin by the pancreas may also be defective and suboptimal. In fact, there is a known steady decline in beta cell production of insulin in type 2 diabetes that contributes to worsening glucose control. Finally, the liver in these patients continues to produce glucose through a process called gluconeogenesis despite elevated glucose levels. The control of gluconeogenesis becomes compromised.
While it is said that type 2 diabetes occurs mostly in individuals over 30 years old and the incidence increases with age. Most of these cases are a direct result of poor eating habits, higher body weight, and lack of exercise.
While there is a strong genetic component to developing this form of diabetes, there are other risk factors - the most significant of which is obesity. There is a direct relationship between the degree of obesity and the risk of developing type 2 diabetes, and this holds true in children as well as adults.
Regarding age, data shows that for each decade after 35 years of age regardless of weight there is an increase in incidence of diabetes.
Diabetes can occur temporarily during pregnancy. Significant hormonal changes during pregnancy can lead to blood glucose elevation causing gestational diabetes. Gestational diabetes usually resolves once the baby is born. However, 35% to 60% of women with gestational diabetes will eventually develop type 2 diabetes over the next 10 to 20 years, especially in those who require insulin during pregnancy and those who remain overweight after their delivery. Women with gestational diabetes are usually asked to undergo an oral glucose tolerance test about six weeks after giving birth to determine if their diabetes has persisted beyond the pregnancy, or if any evidence (such as impaired glucose tolerance) is present that may be a clue to a risk for developing diabetes.
There is an increased risk of gestational diabetes if:
- body mass index (BMI) is 30 or more
- If the previous baby weighed 4.5kg (10lbs) or more at birth
- Gestational diabetes in a previous pregnancy
- Family history of diabetes
- South Asian ethnicity (specifically India, Pakistan or Bangladesh)
The evolution of T2DM follows through different stages. Impaired fasting glucose and Impaired glucose tolerance are the fore-runners of future T2DM (collectively termed as Prediabetes). These states include a proportion of people who belong to the intermediate group, whose glucose levels, although do not meet the criteria for diabetes are nevertheless too high to be considered normal. These patients may develop diabetes in future if their glycemic status is not maintained by modification of lifestyle.
Impaired Fasting Glucose is present when the fasting level is ≥ 110mg/dl and ≤ 125mg/dl and the 2 hour value is < 140mg/dl.2
Impaired Glucose Tolerance is present when the 2 hour value is in the range of ≥140 mg/dl - < 200 mg/dl.
- Standards of Medical Care in Diabetes—2015, Diabetes Care Volume 38, Supplement 1, January 2015
- Definition and Diagnosis of Diabetes and Intermediate Hyperglycemia – Report of a WHO/IDF consultation. Geneva: Whorl Health Organization; 2006