A NATIONWIDE cohort study has revealed that adults diagnosed with type 2 diabetes (T2D) in midlife and old age face a significantly increased risk of developing very late-onset schizophrenia. The research, conducted in Israel, followed nearly 100,000 adults over an average of 14 years, demonstrating that T2D may serve as a key indicator for psychosis monitoring in older populations.
Nationwide Cohort Study Demonstrates Increased Schizophrenia Risk
The study included 99,567 members of a non-profit Israeli health maintenance organisation, born between 1932 and 1952, who had no prior history of T2D or schizophrenia. During follow-up, the incidence of schizophrenia per 10,000 person-years was 0.26 in participants with T2D compared to 0.12 in those without the condition. After adjusting for 20 potential confounding factors, T2D onset was associated with a 50% increased risk of incident schizophrenia (adjusted hazard ratio = 1.53). Complementary analyses consistently supported the primary findings, and the use of antidiabetic medications did not appear to influence schizophrenia risk.
Potential Mechanisms Linking Type 2 Diabetes and Schizophrenia
Researchers suggest several possible explanations for the observed association. Shared genetic factors may increase susceptibility to both T2D and schizophrenia, while stress-related processes common to both conditions could contribute to risk. Cognitive decline and structural brain changes associated with T2D may also trigger psychosis in vulnerable individuals. For some patients, early subclinical symptoms of schizophrenia may coincide with poor self-care and metabolic instability, potentially accelerating the onset of psychosis.
Women with Diabetes Face Highest Risk
The study found that women with T2D had a particularly elevated risk of developing schizophrenia in older age, which may be influenced by factors such as estrogen loss, social isolation, or loneliness. While a trend toward increased risk was observed in men, it was not statistically significant, likely due to smaller sample sizes. Future research is needed to clarify sex-specific mechanisms.
These findings underscore the importance of monitoring mental health in patients with T2D, particularly among older adults. Psychiatrists, geriatricians, and endocrinologists should be aware of the elevated risk of schizophrenia in this population, and clinicians may consider early screening for psychosis in patients with new-onset T2D.
