Causes of Diabetes – Inheritance
CAUSES OF DIABETES
Inheritance
My father had Type 2 diabetes. Am I likely to get it too?
Diabetes is a common disorder in this country and is diagnosed in about three in 100 people. A further two in every 100 have the condition without knowing about it – the ‘missing million’ – bringing the overall figure to about 5%. So in any large family more than one person may be affected, simply by chance. However, certain families do seem to carry a very strong tendency for diabetes. The best example of this is a whole tribe of native American people (the Pima): over half of its members develop diabetes by the time they reach middle age. 
Genes are the parts of a human cell that decide which characteristics you inherit from your parents. The particular genes that you get from each parent are a matter of chance – in other words, whether you grow up with your father’s big feet or your mother’s blue eyes. Similarly it is a matter of chance whether you pass on the genes carrying the tendency for diabetes to one of your children. It is only the tendency to diabetes that you may pass on: the full-blown condition will not develop unless something else causes the insulin cells in the pancreas to fail. Unlike Type 1 diabetes, the actual genes that carry the risk of Type 2 diabetes have not been identified. Nevertheless, Type 2 diabetes has a much stronger family link than Type 1. If either of your parents has Type 2 diabetes, you have a 30% chance of developing prediabetes and about 50% of people with this condition develop diabetes. So the overall risk is about 15%.
I come from an Indian family and number of my relatives have diabetes. I have been told that diabetes is more common in Asian families. Is this true?
It is an unfortunate fact that diabetes is much more common in families who originate from the Indian subcontinent. The risk seems to be related to moving from a subsistence life, where people have to work hard in order to grow enough food for survival, to a comparatively easy life of relative affluence, where food is easily available and hard physical work is no longer a fact of life. Indians who live in an urban environment have a risk of diabetes up to five times greater than that of a white person with a similar lifestyle. People of Indian origin who live in this country must be aware of their risk of diabetes, especially if parents and relatives are affected. As in all cases of diabetes, early diagnosis is vital if complications are going to be avoided.
I’ve been told that people from certain parts of the world are more at risk of diabetes. Could you tell me more about this?
Certain groups of people have extremely high risk of diabetes. The Pima people, a native American tribe who live in Arizona, have a greater than 50% risk of diabetes. Other groups who have developed a sedentary lifestyle, such as South Pacific islanders from Nauru, who have grown rich, have almost as great a risk as the Pimas. Any population which exchanges a harsh rural environment for the relative affluence and inactivity of urban living carries a significant risk of diabetes. Thus rural Hispanics in the USA have a 7% risk of diabetes which increases to 17% in their urban counterparts. There is also a higher risk of diabetes in people of Afro-Caribbean origin.