Causes of Diabetes

The causes of diabetes are not fully understood. However, the causes definitely differ depending on the type of diabetes, whether Type 1 Diabetes or Type 2 Diabetes.

Type 1 diabetes results from the body losing the ability to produce insulin, whereas Type 2 Diabetes usually results from the body losing the ability to use insulin (called “insulin resistance”) even though the body can still produce insulin. However, there is also a less common form of Type 2 Diabetes where the body’s ability to produce insulin is also affected.

The causal factors for each type include:

  • Type 1 Diabetes (Juvenile Diabetes). This type of diabetes is an Autoimmune Disease, which means that the body’s own immune system cells actually attack the good cells of the pancreas. It is this immune damage to the pancreas that causes the body to lose the ability to produce insulin. The triggers for the autoimmune reaction are not fully understood. There are associations with viruses. There is also some genetic basis, with the inheritance rates usually quoted in studies ranging from about 4% to 11%, depending on the particular research study. Read more about: Causes of Type 1 Diabetes.
  • Type 2 Diabetes (Non-Insulin Dependent Diabetes Mellitus). This type of diabetes usually results from a loss of sensitivity to insulin. This means that the body’s cells lose their insulin sensitivity leading to insulin resistance, and the body actually produces more insulin to try to overcome this resistance. Paradoxically, the body then has too much insulin in the blood, called hyperinsulinemia (high blood insulin). The causes of this form of insulin resistant Type 2 Diabetes are often related to obesity/overweight and lifestyle issues. This type of insulin-resistant Type 2 Diabetes has a high genetic risk factor where it is inherited from parents. The inheritance rate of Type 2 Diabetes can be as high as 50%, but the children don’t usually get it until their 40’s or 50’s (although there has been an increase in teens being seen with Type 2 Diabetes). Read more about: Causes of Type 2 Diabetes.
  • Type 2 Diabetes Insulin-Deficient Type. Although Type 2 Diabetes usually results from insulin resistance, there is a less common subtype that results from insulin deficiency. This means that the body produces too little insulin.
  • Gestational Diabetes: This form of diabetes in pregnant women seems to be a form of insulin resistance, similar to Type 2 diabetes. The increase in weight and various other body changes seem to trigger conditions similar to those causing Type 2 Diabetes. Women who get gestational diabetes usually find it goes away after the birth of the child, but they are at higher risk of Type 2 Diabetes later in life.
  • Pre-Diabetes (Impaired Glucose Tolerance). This is usually an early form of insulin-resistant Type 2 diabetes, and the causes are similar. Read more about: Causes of Pre-Diabetes.

Secondary Diabetes: It is uncommon for diabetes to have a single clear cause due to another disease, but it can occur. This is called “secondary diabetes” meaning that the diabetes is the “second” disease with another primary (“first”) disease as the original cause. When a person is first diagnosed as having the symptom of hyperglycemia (high blood glucose), there are various other diseases that need to be considered.

Examples of other (primary) diseases that cause secondary diabetes include:

Drug Diabetes: There are a number of drugs and medications that can sometimes cause a form of secondary diabetes or diabetes-like symptoms:

Note: This site is for informational purposes only and is not medical advice. See your doctor or other qualified medical professional for all your medical needs.