Diabetes is one of the most prevalent non-communicable disease conditions worldwide, with prevalence numbers continuously outnumbering prior predictions. According to the latest atlas from the International Diabetes Federation, there are currently 537 million adults living with diabetes, a number that is expected to increase to a staggering 783 million within the next 20 years (
Sun et al., 2022
). The vast majority of these people have type 2 diabetes, the form of diabetes characterized by a combination of insulin resistance and (relative) insulin deficiency and with clear links to obesity and sedentary life-styles. The process leading to type 2 diabetes probably starts many years before actual disease onset, explaining the high number of people living with a form of prediabetes, and continues to progress after diagnosis with continuing decline in beta-cell function. This explains why already more than one in five persons living with type 2 diabetes require (intensive) insulin treatment (
Garg et al., 2018
).

Since insulin and glucose can cross the blood-brain barrier, there is increasing attention for possible associations between diabetes and neuropsychiatric or neurodegenerative conditions, as exemplified by the PRIME project (
https://prime-study.eu/
). The recent reporting of genetic overlap between type 2 diabetes (and obesity) with several of these neuropsychiatric disorders, including Alzheimer’s Disease (AD), autism, attention-deficit hyperactivity disorder (ADHD) and major depressive disorder (MDD), provide further insight in common pathophysiological pathways linking these conditions (
Fanelli et al., 2022
).

Links between diabetes and mood disorders that are typically bi-directional (
Nouwen et al., 2010
,
Mersha et al., 2022
,
Yu et al., 2015
), have long been thought to be clinically explained, e.g. by the high burden of disease and adverse lifestyle habits, respectively. Although these factors definitely play a role, the genetic overlap between type 2 diabetes and MDD provides evidence for a biological basis.




Sources - https://www.sciencedirect.com/science/article/pii/S0149763424002446