Study finds prescription of antidepressant and antipsychotic drugs common ahead of type 2 diabetes diagnosis

Almost three in ten people with type 2 diabetes (T2D) in Scotland were prescribed antidepressants before they were diagnosed with diabetes, according to new research being presented at the European Association for the Study of Diabetes (EASD) conference, held online this year.

The study, from Ms Charlotte Greene, Professor Sarah Wild and colleagues at the University of Edinburgh, UK, also found that just over one in ten people were prescribed antipsychotics prior to diagnosis of T2D.

The aim was to provide information about patterns of antidepressant and antipsychotic drug prescribing prior to the diagnosis of diabetes. This is part of a broader piece of research, which aims to look at whether prescribing patterns of these drugs in people with diabetes have changed over time and whether these drugs affect the risk of complications in people with diabetes.

The study used the Scottish Care Information-Diabetes Collaboration (SCI-Diabetes) dataset, which contains information on almost all patients diagnosed with diabetes in Scotland, to provide information on the prevalence and patterns of antidepressant and antipsychotic drug prescribing in the four years prior to diagnosis of T2D in 266,186 adults.

22.5% were prescribed antidepressants, 5.3% were prescribed antipsychotics and 6.6% were prescribed both antidepressants and antipsychotics. (Comparable figures aren’t available for the general population.)

Of those prescribed antidepressants, 32.9% were prescribed a selective serotonin reuptake inhibitor (SSRI), 30.5% a tricyclic antidepressant and 9.9% another type of antidepressant.  The remaining 28.6% were prescribed more than one type of antidepressant. 

Of those prescribed antipsychotics, 80.4% were prescribed a first-generation drug, 14.2% a second-generation drug and 5.5% antipsychotics of more than one type.

Those prescribed antidepressants and or antipsychotics were more likely to be women than those not given the drugs.  They were also more likely to live in more socioeconomically deprived areas, be current smokers, obese and have high blood pressure and high cholesterol.

Hospital admissions for psychiatric disorders were also more common in those prescribed antidepressants or antipsychotics.

The study’s authors say that while it isn’t known why the prescription of these drugs is common ahead of T2D diagnosis, mental illness is thought to increase the risk of T2D for several reasons. 

For example, people with mental illness are more likely to have a poor diet, be physically inactive, smoke and misuse alcohol, than people without mental illness. They are also more likely to live in socioeconomically deprived areas – all of which are associated with a higher risk of T2D.

Ms Greene adds: “Additionally, some antidepressants and antipsychotics are thought to increase risk factors related to the development of type 2 diabetes, including weight gain, independently of mental illness.

“More research is needed to investigate prescription patterns after diabetes diagnosis and to determine whether use of these drugs affects the risk of complications of diabetes including heart disease, stroke, and retinopathy.”