High blood glucose levels linked with depression risk

Researchers from Boston show that high blood glucose levels can affect emotions and raise depression risk.
Whilst there is known to be a strong link between type 1 diabetes and depression, the connection has not been well understood with researchers only able to offer speculation as to which factors play a part in the increased risk of depression. However, new research suggests that high blood sugar levels are likely to play a role in the increased risk of depression.
The study involved 19 individuals, 8 of which have type 1 diabetes and the other 11 were control subjects without any form of diabetes. The average age of participants was 26 for the diabetic participants and 29 for the control group. None of the participants had depression.
The researchers used magnetic resonance imaging (MRI) to monitor brain activity at different blood glucose levels. Brain activity when blood glucose levels were between 5.0 and 6.1 mmol/l and again when blood sugar levels had been raised to between 10 and 11.1 mmol/l through intravenous infusion of glucose.
The researchers found that high blood glucose levels lead to weaker connections in the brain related to self-perception and emotions in type 1 diabetic participants compared with control subjects. In addition, the research team noted that the connections were weaker still for diabetic participants that had poorer diabetes control (a higher HbA1c level).
In their investigation of what may be causing the weaker brain connections, the researchers found that the rise in blood glucose levels, in the participants with type 1 diabetes, increased levels of glutamate in parts of the brain responsible for emotions and a factor in depression.
Whilst the study was small, the research suggests that improving blood glucose control and reducing the number of hours per day spent with too high sugar levels, could have benefits towards improving mood and decreasing symptoms of depression.