The research, published in Diabetologia (the journal of the European Association for the Study of Diabetes [EASD]), was conducted by Associate Professor Roger E. Henriksen and his colleagues at Western Norway University of Applied Sciences.
As per the study, loneliness creates a chronic and sometimes long-lasting state of distress which may activate the body's physiological stress response. Though the exact reason cannot be detected, but it is understood that T2D develops due to temporary insulin resistance brought on by elevated levels of the stress hormone cortisol.
Also due to loneliness, there is a change in our eating behaviour. This causes an increased appetite for carbohydrates and subsequently elevated blood sugar levels.
Previous studies have found an association between loneliness and unhealthy eating including higher consumption of sugary drinks and foods rich in sugars and fats.
Out of 24,024 people who participated in the study, 1,179 (4.9 per cent) went on to develop T2D over the course of the study (1995-2019). These individuals were more likely to be men (59 per cent vs 44 per cent) and had a higher mean age (48 years vs 43 years) than those without T2D. They were also more likely to be married (73 per cent vs 68 per cent) and have the lowest level of education (35 per cent vs 23 per cent). Feelings of loneliness were reported by 13 per cent of participants.
The study found that higher levels of loneliness at baseline were strongly associated with a higher risk of T2D when measured 20 years later. After adjusting for age, sex and education level they found that participants who responded 'very much' when asked whether they had felt lonely were twice as likely to develop T2D than those who did not feel lonely.
Further analysis showed that this relationship was not altered by the presence of depression, sleep-onset insomnia or terminal insomnia, although the team did find evidence of a link to sleep maintenance insomnia.
Although their study did not examine the exact mechanisms involved, the researchers note that social support, influence and engagement may have positive effects on health-promoting behaviours. For example, advice and support from a friend may influence an individual's health-related choices and positively affect their diet, physical activity level and overall feelings of stress. Fewer social ties and a lack of these positive influences can make lonely people more vulnerable to behaviour which could increase the risk of developing T2D.
