The exact cause for type I diabetes is unknown. Genetic (family history) and environmental factors are likely to play some role in type I diabetes. 

There is no single cause for type 2 diabetes, but these are well known risk factors.

• Overweight or obesity

• Family history of diabetes

• Unhealthy diet

• Physical inactivity and sedentary lifestyle 

• Increasing age

• Hypertension

• High levels of cholesterol and triglycerides 

• Ethnicity

• Impaired Glucose Tolerance (IGT)*

• Polycystic ovary syndrome (PCOS)

• History of gestational diabetes

* Impaired Glucose Tolerance (IGT) is a category of higher than normal blood glucose, but below the threshold for diagnosing diabetes.

The reasons for the sharp increase in the number of people developing diabetes are the changes in diet and physical activity which is related to the rapid development and urbanization.