Is diabetic neuropathy associated with increased risk of developing mental disorders?

It is largely unknown whether individuals with diabetic neuropathy face an increased risk of developing mental illness. Therefore, in a population-based cohort study, we aimed to examine whether individuals with diabetic neuropathy are at elevated risk of being diagnosed with a mental disorder compared to diabetes-duration-matched individuals without diabetic neuropathy.

We used the nationwide Danish registers to identify all individuals diagnosed with diabetic neuropathy between January 1, 1996, and January 1, 2019. For each of these individuals, we identified up to five individuals with diabetes, matched on the duration of illness, who were not diagnosed with diabetic neuropathy. We then compared incidence rates of mental disorders between individuals with diabetic neuropathy and the diabetes-duration-matched individuals using a Cox proportional-hazards model.

Individuals with diabetic neuropathy had a substantial and statistically significant increased risk of being diagnosed with any mental disorder (age- and sex-adjusted hazard rate ratio: 1.40, 95% CI: 1.31-1.48) as well as all specific mental disorders (psychotic disorder, bipolar disorder, unipolar depression, and/or anxiety disorder) compared with diabetes-duration-matched individuals without diabetic neuropathy.

Diabetic neuropathy appears to be associated with a substantially increased risk of developing a mental disorder. Knowledge of the potential mechanisms underlying this association could inform prevention and treatment and should therefore be pursued further.