Diabetes and genetics
Wednesday, 4 November 2020
Is diabetes a genetic condition?
Type 1 and type 2 diabetes are both quite different in their development but you can inherit a susceptibility or predisposition to developing the condition from your parents. However, there is usually something in the environment that triggers diabetes to develop.
Type 1 diabetes
Type 1 diabetes is an autoimmune condition where the body destroys its own beta cells – these cells produce insulin in the pancreas. Lifelong insulin therapy is required to treat the condition. The interaction between genes and the environment is thought to stimulate the immune response that destroys the cells. Type 1 diabetes cannot be prevented.
There is a genetic risk for developing type 1 diabetes, with a first degree relative having a higher risk of developing type 1 diabetes than unrelated people in the general population. Those with a family member with type 1 diabetes have 10-15 times the risk of developing it. But 80% of people living with type 1 diabetes have no family history of the condition.
Environmental factors act as initiators or accelerators of beta cell destruction. The World Health Organization advises that the incidence of type 1 diabetes is increasing. It considers global environmental factors as potential “initiators”. Research is currently assessing microbes such as viruses and how hygiene and exposure to microbes affects immune development. All of these are potential initiators.
Type 2 diabetes
Type 2 diabetes is caused by insulin resistance, where your body loses its sensitivity to insulin. As the condition progresses, your pancreas is not able to make enough insulin. Type 2 diabetes accounts for around 90% of all diabetes diagnoses in Australia.
There is a stronger family history link for developing type 2 diabetes compared to type 1 diabetes. But as families tend to have similar lifestyles, it can be difficult to determine if type 2 diabetes is caused by lifestyle or genetics.
People who are at higher risk of developing type 2 diabetes include those from Aboriginal or Torres Strait Islander, Pacific Islander, the Indian sub-continent, South-East Asian, Arabic and African ethnic backgrounds.
The risk of developing type 2 diabetes in a lifetime is 40% if you have one parent diagnosed with it, and if both parents are affected the risk of developing it increases to 70%. First degree relatives are three times more likely to be diagnosed with type 2 diabetes than someone with no family history.
It is important to consider that while there is a strong heritability for type 2 diabetes in families, lifestyle plays a significant role in the development. The factors that lead to increased risk of type 2 diabetes include carrying extra weight, particularly around the waistline, being sedentary, having a high intake of saturated fat, having a high stress level, and smoking. These lifestyle risk factors may be modified.
Maturity-Onset Diabetes of The Young (MODY)
Maturity-onset Diabetes of The Young (MODY) is a genetic defect or mutation of a particular gene that limits the ability of the pancreas to produce insulin. There are over 10 different gene mutations that can cause MODY and this type of diabetes usually occurs in adolescence and early adulthood. Depending how MODY presents in the individual it can be confused with either type 1 or type 2 diabetes, depending on the timeframe of onset of presentation and the weight range of the person with MODY.
Typically, if there is a family history in multiple generations of diabetes, MODY genes may be present.
Treatment for MODY can be either insulin or sulfonylureas.
Gestational Diabetes (GDM)
Gestational Diabetes Mellitus (GDM) is a form of diabetes that occurs in pregnancy. Women are usually screened between 24-28 weeks of pregnancy for gestational diabetes. Hormones produced during the pregnancy reduce the action of the mother’s insulin, leading to insulin resistance.
Women that experience GDM are at increased risk of developing type 2 diabetes in the next 10 years. Some women can have ongoing high blood glucose levels after delivery and be diagnosed at that point.
Women who have GDM may have some of the same genetic risks that all people with type 2 diabetes have. The baby may also be at higher risk of developing type 2 diabetes later in life.
By Alison Crow, Pharmacist CDE