Loneliness may be a factor that increases the risk of type 2 diabetes but is not mediated by depression or insomnia, according to new study findings.
A study published in Clinical Child Psychology and Psychiatry found that loneliness could be a factor that increases the risk of type 2 diabetes, and the relationship is not mediated by depression or insomnia. The result supports the inclusion of loneliness in future clinical guidelines.
Past literature has demonstrated an association between psychological stress and type 2 diabetes. Loneliness, which reflects a state of distress linked to perceived lacking quantity and quality of social relationships compared with the quantity and quality wanted, would fall under this psychological stress category. This study aimed to identify the effect of loneliness on type 2 diabetes.
Data for this study were taken from the Trøndelag Health Study (HUNT study) conducted in Norway. The surveys HUNT2 (1995-1997), HUNT3 (2006-2008), and HUNT4 (2017-2019) were used. There was a total of 34,992 participants who provided data for all 3 surveys. Participants with self-reported type 1 diabetes or who met the criteria for type 2 diabetes and people who had a metabolic disorder were excluded from the study.
Loneliness was measured by asking the participants if they had felt lonely in the last 2 weeks, with responses of “no”, “a little”, “a good amount”, and “very much” as response options. Anxiety and depression were measured with the Hospital Anxiety and Depression Scale. Insomnia was measured using the sleep questionnaire included in the HUNT3 survey.
There were 24,024 participants who were included in the analyses, of whom 1179 (4.9%) developed type 2 diabetes during the study period of 1995 to 2019. Participants with type 2 diabetes were most often men (59.3%) and had a higher mean age (47.9 years vs 43.3 years) compared with those without type 2 diabetes. Patients with type 2 diabetes were more often married (73.1% vs 67.5%) and had the lowest education level (34.8% vs 23.3%).
Various degrees of loneliness were reported by 12.6% of the participants. Participants who reported higher levels of loneliness had higher odds of type 2 diabetes (adjusted odds ratio [OR], 1.13; 95% CI, 1.00-1.28). Participants who had responded to the loneliness survey with “very much” had 2 times the risk of type 2 diabetes in a 20-year follow-up found in HUNT4 (adjusted OR, 2.19; 95% CI, 1.16-4.15).
Symptoms of depression were not a mediator for the effect of loneliness on type 2 diabetes after adjusting for sex, age, and education. Sleep-onset insomnia and terminal insomnia were also not found to be a mediator for the effect.
There were some limitations to this study. The large cohort and follow-up makes it so that depressive symptoms cannot be completely ruled out as a mediator between loneliness and type 2 diabetes. Depression was reported 10 years after loneliness and 10 years before type 2 diabetes. Depression can be episodic compared with loneliness, which may make it hard to relate them. Insomnia could also be considered episodic in this way.
The researchers concluded that a 20-year follow-up survey found that a 2-fold increased risk of type 2 diabetes was associated with a high degree of loneliness.
Henriksen RE, Nilsen RM, Strandberg RB. Loneliness increases the risk of type 2 diabetes: a 20 year follow-up–results from the HUNT study. Diabetologia. Published online September 28, 2022. doi:10.1007/s00125-022-05791-6