It is well recognised that increasing rates of type 2 diabetes are mainly driven by obesity and lifestyle factors. But that’s not the whole story. Genetics and epigenetics – changes in gene expression – also play an important role.
We are starting to see an increase in type 2 diabetes in leaner people at a much younger age than usually associated with the disease. This means in addition to focusing on good diet and exercise, we need better awareness of groups most at risk of type 2 diabetes.
These include many ethnic groups, women with a history of gestational diabetes and people with a family history of diabetes. In my clinical practice, I have seen teenagers and even children as young as seven, as well as younger patients of Asian, African and Middle Eastern origin with type 2 diabetes.
Among Indigenous people in Central Australia, rates of diabetes are some of the worst in the world, at around three times that of non-Indigenous people. Studies in some remote communities suggest a prevalence of type 2 diabetes of up to 30%, compared to a rate of around 5% in the non-Indigenous population.
All this indicates lifestyle decisions alone can’t be responsible. We need to stop the blame and shame for a condition that has an association with lifestyle, but for many is a consequence of the toxic mix of genetics and modern life.
More than just lifestyle changes
Type 2 diabetes accounts for more than 90% of all diabetes cases and affects mainly middle-aged and older people who are overweight or obese.
Type 2 diabetes is thought to occur from a combination of factors: when the pancreas can’t produce enough insulin; and when the insulin is unable to do its job, to regulate blood sugar.
Why these two factors happen is not completely understood. The physiology may vary between different populations but broadly relates to excessive storage of fat, reduced muscle activity with poor uptake of glucose and genetic predisposition.
In contrast, type 1 diabetes is unrelated to lifestyle factors, has onset in children or young adults and relates to a complete destruction of the insulin-producing (beta) cells in the pancreas.
The cause is not known but may relate to genetic predisposition and an environmental trigger, such as a virus or toxin.
Both types of diabetes may cause a range of serious complications, including loss of limbs, if not aggressively treated.
Genetics and epigenetics
So why are the young and slim getting type 2 diabetes? One theory is epigenetics.
Epigenetics describes the biological process in which environmental factors may affect the expression of genes (where the gene codes for a particular biological function) rather than the alteration of genes themselves.
This process can occur as early as in the womb – before the child is born – with consequences that affect genetic expression for much of their lives.
Conditions such as obesity and gestational diabetes, where women with no pre-existing diabetes develop it during pregnancy, have the potential to alter gene expression in a developing foetus.
This may lead to a predisposition for a range of chronic illnesses, including diabetes. Some ethnic groups are at much greater risk of gestational diabetes; Indigenous women have rates nearly double that of non-Indigenous women.
The exact mechanisms that create such predispositions aren’t known and are the subject of intense ongoing research.
Many studies have shown early aggressive treatment before any sign of diabetes damage can better prevent complications, such as heart disease, kidney failure or blindness.
Aggressive treatment means we should aim for blood sugar levels to be as close to normal – between 4 and 5.5 mmol per litre and non-fasting glucose of 4 to 7.8 mmol per litre – as possible. This often requires medication in addition to intensive lifestyle changes.
Not only is it more expensive to treat complications once they are symptomatic but the outcomes of doing so are poorer. Comparing some of the key diabetes studies over the past 20 years, we found a strategy targeting near-normal blood glucose levels resulted in fewer kidney, eye and heart complications compared with those that had a more relaxed target.
The main factor limiting perfect control of blood glucose is hypoglycaemia. Characterised by low blood glucose levels, it can cause discomfort, confusion or even coma in extreme cases.
For this reason, we need newer medications which can better control blood sugar without the risk of hypoglycemia. Until we get these, the risk makes it acceptable to have less-than-perfect control in some instances.
Modern drug treatment has improved overall, however, and we have access to a range of therapeutics that can be used effectively from early in the disease. Lifestyle measures are an important part of treatment but their benefit may diminish as type 2 diabetes progresses or gets worse over time.
Removing the stigma
Governments must recognise the importance of access to effective new therapies for diabetes as well as adequately fund clinical services to properly manage this complex chronic illness – especially in highly endemic areas such as remote Indigenous communities.
Premature death rates for people with type 2 diabetes are around three times greater than in the general population, largely due to heart disease and stroke. Adjusted years of life lost are greater for those with type 2 diabetes than for those with breast, lung or bowel cancer.
There is a significant stigma and shame attached to the diagnosis of type 2 diabetes, particularly in younger patients. This adds an unfortunate barrier to successful treatment. Until this is improved, we will continue to under-treat our patients and misinform our health providers.