Study Suggests Improving Blood Sugar Control Could Help Prevent Dementia

21 Sep 2015 --- A study of 350,000 patients with type 2 diabetes shows that those with poor blood sugar control have 50% higher risk of being admitted to hospital in future for dementia as those with good control. The research, which suggests improving blood sugar control could prevent many cases of dementia, is by Dr Aidin Rawshani, National Diabetes Register and Institute of Medicine, Gothenburg, Sweden, and colleagues, and is presented at this year's annual meeting of the European Association for the Study of Diabetes (EASD) in Stockholm.

Evidence is growing that diabetes increases the risk of future declines in brain function. However, there have as yet been no studies on how blood sugar control - as measured by glycated hemoglobin or HbA1c - affects the risk of a future dementia diagnosis. In this study, the authors studied extensive clinical data to explore the association between HbA1c and the risk of hospitalization for dementia among persons with type 2 diabetes.

The researchers identified all patients with type 2 diabetes and no known hospitalization for dementia who were registered in the Swedish National Diabetes Registry between January, 2004, and December, 2012. These patients were followed up until hospital admission for dementia, death, or end of follow-up on Dec 31, 2012. Computer modeling was used to calculate the link between HbA1c, and dementia, which also adjusted for variables including age, sex, duration of diabetes, marital status, income, education, smoking status, systolic blood pressure, body mass index, estimated kidney function, statins, levels of urine in protein, type of diabetes medication, atrial fibrillation, stroke and blood pressure medications.

In a cohort of 349,299 patients with mean age of 67 years at baseline, 11,035 patients (3.2%) were admitted to hospital with a primary or secondary diagnosis of dementia during a mean follow-up of 4.6 years. Patients with a HbA1c of 10.5% or higher (worst blood sugar control) were 50% more likely to be diagnosed with dementia compared to those with HbA1c of 6.5% or less (most well controlled). Previous stroke in these patients made them 40% more likely to develop dementia than those without stroke.

The authors say: "The positive association between HbA1c and risk of dementia in fairly young patients with type 2 diabetes indicates a potential for prevention of dementia with improved blood sugar control."

Improving blood sugar control in type 2 diabetics requires careful menu planning. A diet with plenty of fresh non-starchy vegetables, protein and healthy fats has been shown to regulate blood sugar levels better than one which includes starchy carbohydrates, even in small amounts. Data from the longitudinal Adult Changes in Thought (ACT) study has linked to high blood sugar even in non-diabetics, looking at blood sugar ranges well within normal (non-diabetic) levels.

As yet, the exact mechanisms are unknown, but it is thought that the effects of glucose on inflammation, vascular disease and the effects of insulin are all involved. It has also been discovered recently that high blood sugar levels are associated with a smaller hippocampus – the area of the brain responsible for learning and memory.

Dr Rawshani says, “The role of insulin in the brain is debated; some suggest that insulin shortage might reduce the secretion of the protein called insulin-degrading enzyme, this protein might also have a function on Beta-amyloid peptide degradation. Insulin has attracted much attention in brain research lately, it has traditionally been thought that insulin does not have an effect on the human brain. However insulin has been shown to have regulatory effects in the brain regarding energy and food intake and also an effect on modulation of memory, in some studies.”