This research states that Insulin has been implicated in many neurological processes including synaptic plasticity and cognition, whilst neurons are dependent on glucose as their major energy source. There may be an attractive target for clinical intervention as glycaemia can be modulated by both lifestyle factors and pharmacological agents. There was no consistently strong evidence for a causal effect of glycaemic factors on the other seven psychiatric disorders considered. The relationship between fasting insulin and anorexia nervosa was supported by a suite of sensitivity analyses, with no statistical evidence of instrument heterogeneity or horizontal pleiotropy.

The researchers employed genetic variants rigorously associated with three glycaemic traits (fasting glucose, fasting insulin, and glycated haemoglobin) as instrumental variables in a two-sample Mendelian randomisation analysis to investigate the causal effect of these measures on the risk for eight psychiatric disorders.There has been increasing interest in the relationship between glycaemic regulation and psychiatric illness.  As a result, we can say that; In this study, the researchers have applied an effective approach to probe the causal effects of glycaemic traits on the risk for psychiatric disorders and observed a significant protective effect of elevated fasting insulin levels on the risk of anorexia nervosa (AN). Further investigation is required to explore the relationship between insulin levels and anorexia.

Ref: https://www.nature.com/articles/s41386-020-00847-w