People who have diabetes diagnosed in midlife have a higher risk of cognitive decline over the following 20 years compared to people with normal glucose levels. A prospective study done in the USA showed that there was a 19% increased risk of cognitive decline over the 20 years for those who had diabetes. This meant that having diabetes aged cognitive function by about five more years than normal.
The level of decline was associated with the degree of control of the diabetes. Those with HbA1cs over 7% were more at risk than those with a better degree of control. Increased duration of diabetes also led to a higher risk.
The study reviewed 13,351 year olds who were aged 48-67 at the start of the study for 20 years. Associate professor of epidemiology Elizabeth Selvin of John Hopkins University said of her findings, ” The lesson is that to have a healthy brain when you are 70, you need to eat right and exercise when you are 50. Maintaining cognitive function is a critical aspect of successful ageing. Preventing diabetes and improving glucose control in people with diabetes offers important opportunities for preventing cognitive decline and delaying progression to dementia”.