A recent study has linked loneliness to double the risk of diabetes.
Feelings of loneliness are associated with a much greater risk of developing type 2 diabetes (T2D), according to recent research that was published in Diabetologia, the journal of the European Association for the Study of Diabetes.
Western Norway University of Applied Sciences Associate Professor Roger E. Henriksen and his team conducted the study. It investigated the relationship between loneliness and the probability of developing T2D as well as the role of insomnia and depression.
A rising amount of evidence indicates a connection between psychological stress and someone’s likelihood of getting T2D. Loneliness causes a persistent and, in certain cases, long-term state of distress, which may trigger the body’s physiological stress response. While the exact mechanisms are unknown, this response is believed to play a key part in the development of T2D through mechanisms such as temporary insulin resistance caused by high levels of the stress hormone cortisol.
This process also affects how the brain controls eating behavior, which results in an increase in the desire for carbs and a consequent rise in blood sugar levels. Previous research has linked unhealthy eating, such as consuming more sugary beverages and foods high in fat and sugar, with loneliness.
The researchers used data from the HUNT study, a collaboration between the HUNT Research Centre (Faculty of Medicine and Health Sciences, Norwegian University of Science and Technology [NTNU]), Trøndelag County Council, the Central Norway Regional Health Authority and the Norwegian Institute of Public Health. This database contains the health information (from self-reported questionnaires, medical examinations, and blood samples) of more than 230,000 people and was obtained via four population surveys: HUNT1 (1984-1986), HUNT2 (1995-1997), HUNT3 (2006-2008) and HUNT4 (2017-2019).
Baseline information for 24,024 participants was taken from HUNT2 after excluding individuals with metabolic disorders, type 1 and type 2 diabetes, and those for whom blood test data were not available. T2D status was the main outcome variable and was based on HbA1c (glycated hemoglobin – a measure of long-term blood sugar control) being greater than 48mmol/mol when measured in the HUNT4 survey.
Loneliness was gauged from the HUNT2 data survey whether they had felt lonely over the previous 2 weeks and was measured on a four-point scale (‘no’, ‘a little’, ‘a good amount’, and ‘very much’). The severity of depression symptoms was assessed using a questionnaire completed during HUNT3 which consisted of 7 questions, each scored on a scale of 0-3 for a total of 0-21 points, with higher scores indicating more severe symptoms. Individuals with insomnia were identified based on their answers to the questions: ‘How often in the last 3 months have you: ‘had difficulty falling asleep at night’, ‘woken up repeatedly during the night’ and ‘woken too early and couldn’t get back to sleep’, respectively. These were asked as part of HUNT3 and participants could choose one of three answers: ‘never/seldom’, ‘sometimes’, and ‘several times a week’.
Out of 24,024 people, 1,179 (4.9%) went on to develop T2D over the course of the study (1995-2019). These individuals were more likely to be men (59% vs 44%) and had a higher mean age (48 years vs 43 years) than those without T2D. They were also more likely to be married (73% vs 68%) and have the lowest level of education (35% vs 23%). Feelings of loneliness were reported by 13% 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 behaviors. For example, advice and support from a friend may influence an individual’s health-related choices and have a positive effect on 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 behavior which could increase the risk of developing T2D.
The researchers advise that loneliness should be included in clinical guidelines relating to T2D. They say: “It is important that healthcare providers are open to dialogue about an individual’s concerns during clinical consultations, including with regard to loneliness and social interaction.”
The authors recommend that further research is carried out into the mechanisms at play in the link between loneliness and T2D as well as the roles played by insomnia and depression. They conclude: “Questions to be answered are the extent to which loneliness leads to the activation of stress responses, the extent to which loneliness affects health-related behavior, and, importantly, how these two pathways interact in terms of contributing to an increased risk of T2D.”
Reference: “Loneliness increases the risk of type 2 diabetes: a 20 year follow-up – results from the HUNT study” by Roger E. Henriksen, Roy M. Nilsen and Ragnhild B. Strandberg, 28 September 2022, Diabetologia.
The study was funded by the Western Norway University of Applied Sciences.