I have often heard having a serious mental illness it worse than diabetes and smoking. Mental illness is 'as bad for life expectancy as smoking', experts warn
Mental illness is 'as bad for life expectancy as smoking' link
The daily mail article faithfully summarizes the results of this scientific article.
A meta‐review, or review of systematic reviews, was conducted to explore the risks of all‐cause and suicide mortality in major mental disorders. ... All disorders had an increased risk of all‐cause mortality compared with the general population, and many had mortality risks larger than or comparable to heavy smoking. ... The excess risks of mortality and suicide in all mental disorders justify a higher priority for the research, prevention, and treatment of the determinants of premature death in psychiatric patients.
The questioner expressed a particular interest in bipolar disorder, and deaths by natural causes as opposed to suicide. Table 3 reviews research that shows bipolar disorder has a reduced life expectancy between 8.5 and 13 years. The discussion mentions that people with bipolar disorder commit suicide at more than 10 times the rate of the general population, but they don't break down the reduced life expectancy by suicide vs not suicide.
Other research articles come to a broadly similar conclusion.
... The median years of potential life lost (due to mental illness) was 10 years (n = 24 studies). We estimate that 14.3% of deaths worldwide, or approximately 8 million deaths each year, are attributable to mental disorders.
The introduction of this scientific paper reviews the existing scientific literature. It summarizes the existing science as follows:
People with severe mental illness (SMI), particularly schizophrenia, bipolar disorder and major depressive disorder, have an average mortality rate that is 2‐3 times higher than the general population [1-3], corresponding to a 10‐25 year shortened life expectancy [2-9]. The most common causes of death in people with SMI are physical diseases .
This review article found that people with bipolar disorder are more likely to die from natural causes than the general population. This is particularly true for cardio-vascular disorders.
RESULTS: ... mortality ratios for death from natural causes and from specific general medical conditions, such as cardiovascular, respiratory, cerebrovascular, and endocrine disorders, were significantly higher among patients with bipolar spectrum disorders in most studies. ... Cumulatively, cardiovascular disorder appeared to be the most consistent cause of excess mortality in larger studies.
CONCLUSIONS: The available evidence suggests that bipolar spectrum disorders are associated with increased premature mortality secondary to general medical illnesses. Unhealthy lifestyle, biological factors, adverse pharmacologic effects, and disparities in health care are possible underlying causes for this excess mortality.
Conclusion: Serious mental illness poses serious physical health risks and is strongly linked to shorter life span.