Insulin resistance is related to the duration and severity of depression. Kathleen Watson et al write this in a research letter published in JAMA Psychiatry.
Insulin resistance was already known to be a risk factor for major depressive disorder. The researchers wanted to know whether there is also a relationship with certain characteristics thereof. For their research they draw on the Netherlands Study of Depression and Anxiety (NESDA), a longitudinal study into the course and consequences of anxiety and mood disorders. They divided 1,269 participants into three groups: currently suffering from depression, depression in remission, and participants with no history of depression.
They examined whether there was a relationship between (characteristics of) depression and surrogate markers of insulin resistance. Those markers were the Quicki (quantitative insulin sensitivity index) and the ratio between triglyceride and HDL. Based on previous studies, values have been determined for both that indicate insulin resistance.
The participants with insulin resistance (based on the Quicki value) were on average older, less educated, and had a higher BMI. After adjusting for age, gender, alcohol use and education, there was a relationship between insulin resistance and having a depressive disorder, but not with having experienced it.
Both markers were related to the severity of the depression, but only one of them to the duration. The markers were not related to the severity or duration of the depressions that were now in remission. Such knowledge can contribute to a better typing of depression and possibly also to more tailored treatment.