People who suffer from loneliness have a 32% higher risk of developing type 2 diabetes. That finding, among other evidence, comes from a meta-analysis from Spain and Chile that included data from more than 1 million people. But what psychobiological mechanisms can promote the development of type 2 diabetes in lonely people?

Karl‑Heinz Ladwig, MD, Department of Psychosomatic Medicine and Psychotherapy, Klinik Rechts der Isar, Technische Universität München,Munich, Germany, explained these mechanisms at the continuing Congress of Internal Medicine - Interdisciplinary Diabetology - Without Borders held in Munich and called for more attention to loneliness as a risk factor in diabetes prevention.

“Loneliness hurts like a deep wound and dominates one’s entire sense of life; it has considerable effects on somatic health. Persistent loneliness is also associated with an increased risk of mortality, coronary heart disease and stroke,” Ladwig said.

Who Is Lonely in Germany?

Loneliness is a widespread social phenomenon in Germany: Before the COVID pandemic the prevalence was below 11%, but since then it has remained at a persistently higher level. According to figures from the federal government’s 2024 social report, about 16% to 19% of people in Germany feel lonely.

Loneliness is more pronounced in certain population groups, such as older people living alone, single parents, family caregivers, and young adults. Women are affected by loneliness more often than men, and people with migration or refugee experiences feel lonely particularly often, according to a report by Medscape.

Loneliness can be temporary or situational, tied to specific life events, or it can be a chronic state that a person feels frequently or continuously. The intensity of the feeling of loneliness varies greatly.

Raising Risks

The prospective English Longitudinal Study of Ageing already demonstrated in 2019, using data from more than 4000 participants, how loneliness significantly affected the development of type 2 diabetes over a period of more than 12 years.

Even after controlling for other psychosocial factors such as depression and social isolation — which Ladwig described as the physical component of loneliness — as well as lifestyle factors, loneliness remained significantly associated with type 2 diabetes.

Since that publication, Ladwig said, various population‑based studies have “painted a valid and convincing picture” of the link between loneliness and the onset of type 2 diabetes.

In the meta-analysis mentioned at the beginning, led by first author Yasmín Ezzatvar, Department of Nursing, University of Valencia, Valencia, Spain, nine prospective cohort studies with a total of 1,112,887 people were evaluated. Of these individuals, 50,961 developed type 2 diabetes over a mean follow-up period of almost 11 years. Loneliness was associated with a 32% increased risk of developing type 2 diabetes (HR, 1.32; 95% CI, 1.11-1.57), and social isolation with a 20% higher risk (HR, 1.20; 95% CI, 1.01-1.43).

Stress and Activation

Ladwig outlined the psychobiological mechanisms underlying the association between loneliness and type 2 diabetes. A persistent state of loneliness triggers chronic stress in patients. This affects the autonomic nervous system, with increased heart rate, reduced heart rate variability and a predominance of sympathetic cardiac regulation. There is an imbalance between sympathetic and parasympathetic innervation, he said. 

Added to this is sustained activation of the hypothalamic‑pituitary‑adrenal axis, a central neuroendocrine system for stress regulation, leading to persistent cortisol release. Ultimately, patients suffer from a “blunted reaction” — a reduced capacity for emotional expression and response. “These individuals are exposed to chronic stress and can no longer respond appropriately to an actual stress situation.”

A 2018 review discussed current findings on the link between sympathetic overactivity and metabolic diseases: Autonomic regulation of glucose metabolism associated with sympathetic activation and simultaneous parasympathetic inhibition leads to metabolic disorders. The pathophysiology of metabolic diseases is based on an acute, sympathetically mediated insulin resistance.

Diabetes Prevention

Loneliness and social isolation are significant risk factors for type 2 diabetes and related cardiovascular diseases, Ladwig concluded.

He advocates for greater attention to loneliness in clinical practice. “Integrating psychosocial screening and interventions into everyday clinical practice — not only for depression and anxiety, but also for loneliness — can be crucial. Asking the simple question, ‘Do you feel lonely?’ could be the best way to reach patients.”

This story has been translated from Medscape’s German edition.