Geneticists have confirmed a link between depression and type 2 diabetes.

Researchers have repeatedly sought to determine whether there is a genetic link between depression and type 2 diabetes. Earlier studies concluded that some genetic variants that increase the risk of developing diabetes coincided with those associated with depression. The level of inflammation in the body also played a role in the development of these conditions.  

Now, an international research team led by Ancha Baranova from George Mason University (USA) has analyzed data from the largest genome-wide association studies (GWAS) using a range of modern genetic methods. The scientists identified over 270 loci (the location of a specific gene on the genetic or cytogenetic map of a chromosome), associated with both conditions, 29 of which were discovered for the first time. 

The findings of the study, published in the journal Progress in Neuro-Psychopharmacology & Biological Psychiatry, indicated that type 2 diabetes is linked to both clinical depression and mood disorders: the correlation coefficients were 0.14 and 0.19, respectively. 

The risk of developing diabetes was 24 percent higher in individuals with a hereditary tendency towards depression and 48 percent higher in those predisposed to mood disorders. However, genetic predisposition to diabetes did not significantly influence the risk of developing depression. In other words, individuals prone to depression have an increased risk of developing type 2 diabetes, but diabetics did not show an excessively elevated risk of depression.

Inflammatory processes in the body played a key role in the development of mental disorders and metabolic disorders: heightened immune system activity, characteristic of depressive states, led to chronic inflammation. This, in turn, disrupted metabolism and contributed to the development of type 2 diabetes. 

Thus, the researchers concluded that approximately 60 percent of the genetic variants contributing to the development of diabetes coincided with those related to depression. This discovery helps explain why patients with depression more frequently encounter metabolic disorders and highlights the important role of inflammation in this process. 

The researchers noted that their work could aid in the development of new preventive and therapeutic methods aimed at reducing inflammation levels in the body. Further studies, including those involving non-European populations, will help refine the obtained data.