Type 2 diabetes in mid and late-life is associated with an increased risk of developing cognitive impairment and dementia. All adults, especially once we reach middle age, should have their blood sugar regularly checked by their doctor.
What’s the evidence that diabetes affects dementia risk?
Research consistently shows that people who have type 2 diabetes are on average more likely to develop dementia compared to those without diabetes. Some people who don’t have diabetes have problems with the way their body deals with glucose and insulin. Impaired insulin secretion, insulin resistance and glucose intolerance are also associated with an increased risk of dementia.
Several studies have shown that the presence of type 2 diabetes in midlife is associated with increased risk of dementia, Alzheimer’s disease, vascular dementia and cognitive impairment. Longer duration and greater severity of diabetes may further increase the risk of dementia. A review of relevant studies found that diabetes was associated with a 47% increased risk of any dementia, a 39% increased risk of Alzheimer’s disease, and a 138% increased risk of vascular dementia (Lu F-P, et al. Diabetes and the risk of multi-system aging phenotypes: a systematic review and meta-analysis. PLoS ONE, 2009, 4(1): e4144. doi:10.1371/journal.pone.0004144).
Some studies have shown that diabetics who are treated with medications have better cognitive function and less cognitive decline over time compared to those who are not treated. More research is needed to be sure that effective treatment of diabetes can reduce dementia risk, but it seems likely that good glucose control would reduce the risk of long-term problems including dementia.
Diabetes can be effectively managed. So to reduce your risk of dementia, stroke and heart disease ask your doctor to regularly check your blood sugar and make sure you follow their treatment advice if diabetes or other problems are found.
Evidence rating for diabetes 
Many observational studies have shown an association between having diabetes, especially type 2, and an increased risk of developing dementia. This evidence has been established in meta-analyses.
Longer duration and greater severity of diabetes may increase dementia risk further.
Other studies have shown that diabetes treatment is associated with less cognitive decline.
What is lacking is proof that effectively managing diabetes can reduce dementia risk, but other evidence makes this seem likely and effective treatment is important for other health reasons.
How does diabetes affect dementia risk?
Untreated diabetes over time can lead to blood vessel disease. This increases the risk of dementia because your brain needs healthy blood vessels to keep brain cells functioning well. Diabetes may also contribute to the build up of plaques and tangles in the brain, to inflammation in the brain and to oxidation in brain cells, all of which increase the risk of dementia.
How to reduce your risk of type 2 diabetes
Obesity increases the risk of type 2 diabetes, so it is important to try and maintain a healthy Body Weight.
Regular physical activity can help reduce your diabetes risk, so Mind your Body.
Eating too many fatty, salty and sugary foods will increase your risk of diabetes, so Mind your Diet. Choose foods low in saturated fat, wholegrain breads and cereals, legumes, vegetables and fruits.
Too much alcohol can increase your risk of diabetes, so Mind your Habits.
There are genetic factors that influence your risk of developing diabetes, so some people who do all the right things might still develop diabetes and will need medical treatment.
The most important thing you can do is to have your blood sugar checked regularly by your doctor. If diabetes or other problems are found, follow your doctor’s treatment advice and take any medications as prescribed.
For further information, visit the Diabetes Australia website.
