Professor Calum Sutherland

Diabetes and Dementia

Funding: Diabetes UK and MRC

Insulin is the major hormone that prevents hyperglycemia after a meal. When insulin does not work properly prolonged hyperglycemia occurs (Diabetes), resulting in increased risk of heart disease, blindness, kidney failure, amputation, dementia and stroke.  There are now more than 2 million people in the UK with diabetes. An understanding of the molecular aspects of insulin action will allow us to understand why diabetes occurs and how to develop strategies for prevention and cure, as well as prevent the complications of the disease. For example, insulin regulates the enzyme GSK3, which is closely linked to molecular development of neurodegenerative diseases such as Alzheimer's disease. Our group currently studies three aspects of insulin action.

1) Obesity, insulin resistance and molecular disease. In collaboration with our clinical colleagues at Ninewells Medical School we are establishing whether any of the molecules known to be important in the insulin regulation of gene expression are improperly regulated in human insulin resistance. This work led to the discovery of a novel insulin signalling mechanism. The human studies are generating new information on potential ‘biomarkers’ of early progression to diabetes, which should allow earlier and more efficacious intervention. In addition we are investigating whether obesity alters the activity of CDK5, and how that alters response to drugs used in diabetes. In particular we are establishing whether changes in CDK5 activity may underpin some of the increased risk of cancer in the obese population.

2) Insulin action and the brain. Perhaps surprisingly, insulin receptors are found throughout the brain. Interestingly, there is a higher incidence of Alzheimer’s disease in the diabetic population and it is proposed to be due to defective insulin action on the brain. We have identified a family of proteins regulated by insulin and shown that it is dysregulated in Alzheimer’s disease 13. These proteins (CRMPs) are targeted by GSK3 which is known to be upregulated in diabetes 14-16. Therefore abnormal activity of this family could explain part of the association between diabetes and Alzheimer’s disease. In collaboration with Professor Balfour and Dr Stewart at Ninewells we have identified a specific overnutrition-induced change in behavioural flexibility that is not prevented by the anti-diabetes drug metformin 17 18. In addition we are studying a new function of GSK3, the coordinated control of protein stability. This function provides the opportunity to develop new biomarkers of GSK3 which could have clinical utility in the early diagnosis of dementia, as well as the molecular stratification of diabetes (to improve treatment and care).

3) The genetic contribution to drug response in diabetes. In collaboration with Professor Pearson and McCrimmon at Ninewells we are studying the biology behind the genetic contribution to response to the most common anti-diabetes therapy, metformin. We are investigating why genetic variation in 3 genes influences whether a person with diabetes would respond to metformin and improve their blood glucose. The hope is this information will improve prescribing practice in diabetes, and may help find new therapies for those that can't use metformin.