Schizophrenia is directly and indirectly linked to diabetes. Research also suggests genetic and developmental risk factors can increase the risk for both conditions.

Schizophrenia is a complex psychiatric disorder that’s long been linked to metabolic problems, including type 2 diabetes.

This link has previously been explained by the sedentary lifestyle, poor diet, and antipsychotic use of people with schizophrenia.

But a growing body of evidence suggests there may be an inherent link between the two conditions that’s evident well before any medication use or lifestyle changes.

Let’s take a look at what the research says.

People with schizophrenia have a 2- to 5-fold greater risk of developing type 2 diabetes compared to the general population.

Although traditional risk factors, such as obesity, poor diet, and inactivity, are common in people with schizophrenia some evidence suggests there might be more to the link than these external factors.

An analysis of 16 studies shows that people with schizophrenia may already be at an increased risk of developing diabetes even at the very beginning of the illness — well before any antipsychotic use or long-term poor lifestyle habits have been developed.

Based on blood samples, participants with schizophrenia had a higher risk of type 2 diabetes (higher fasting glucose, insulin, and insulin resistance) compared with the control group.

The results held true even after the researchers took other factors into account, such as:

  • diet
  • exercise
  • ethnicity
  • antipsychotic use

The findings suggest that there may be a direct link between schizophrenia and diabetes. The study authors believe that genetic risk and developmental risk factors (e.g. premature birth, low birth weight) may increase the risk of developing both conditions.

Is schizophrenia linked to type 1 diabetes?

The positive link between schizophrenia and diabetes seems to only occur with type 2 diabetes. In fact, the link is inverted with type 1 diabetes, an organ-specific autoimmune disease.

A Swedish population study from 2019 shows that the incidence of schizophrenia is significantly lower among people with type 1 diabetes, compared to those without type 1 diabetes.

But the risk of developing schizoaffective disorder is no different than that of people in the general population.

The findings may further support the theory that the immune system may play a role in schizophrenia.

Schizophrenia is a debilitating disorder that often interferes with daily functioning and the ability to lead a healthy lifestyle.

High stress levels, obesity, smoking, and other poor health factors are common in schizophrenia and can further contribute to the risk of diabetes.

Schizophrenia is often linked to the following poor health factors:

  • high stress levels (increases cortisol which increases risk for diabetes)
  • lack of sleep
  • obesity
  • poor diet
  • sedentary lifestyle
  • smoking habit
  • unable to hold full time job (leading to poverty)
  • low socioeconomic levels/poverty (affects ability to eat healthy)

The authors of the analysis mentioned above recommend that people with schizophrenia be screened for diabetes. They should also be offered early lifestyle and medication interventions to combat the risk of progression to type 2 diabetes.

Atypical antipsychotics, or second-generation antipsychotics, have fewer serious side effects than their predecessors (first-generation antipsychotics), but they are more likely to cause weight gain and metabolic side effects.

Evidence shows that antipsychotic drugs increase the risk of type 2 diabetes both directly by affecting insulin sensitivity and indirectly by causing weight gain.

So, while there is an increased risk of diabetes in the early stages of schizophrenia, 2019 research shows that the risk rapidly increases after antipsychotics are started.

According to a 2017 systematic review and meta-analysis, large-scale studies have found that people with schizophrenia die 15-30 years earlier than the general population.

In addition, at least 60% of these early deaths are due to cardiovascular causes (rather than due to the central nervous system).

Most people with schizophrenia are treated with atypical antipsychotics. These medications treat the disorder’s positive symptoms (hallucinations, delusions) by reducing dopamine levels in the brain.

Atypical antipsychotics also block a serotonin receptor (5HT2a), which helps create a better balance of dopamine in the brain.

Currently, there are no effective medications for treating the disorder’s negative symptoms (e.g. lack of emotional expression, social withdrawal).

Many people with schizophrenia also participate in various forms of therapy. These include:

Keto diet for schizophrenia/diabetes

Some evidence suggests that the ketogenic (keto) diet—a high-fat, low-carb diet—may help reduce schizophrenia symptoms and also improve metabolic dysfunction.

It’s believed that schizophrenia is linked to reduced energy production in the brain. The keto diet produces “ketones,” which replace glucose as the primary fuel in the brain. This process provides energy to insulin-resistant brain cells.

A 2020 review indicates that several studies demonstrate how a keto diet can help manage symptoms of schizophrenia as well as:

  • improve metabolism
  • reduce obesity
  • decrease inflammation
  • impact neurotransmitters

Schizophrenia has long been associated with metabolic problems, including type 2 diabetes.

While this link can be partially explained by antipsychotic use, obesity, and a sedentary lifestyle, some studies also suggest a direct link between the two disorders.

Researchers suggest that genetic and developmental risk factors may put a person at greater risk for both schizophrenia and diabetes.

If you’re living with schizophrenia, diabetes, or both, it’s important to develop a healthy lifestyle. You might also consider talking with your doctor about the keto diet, as it’s been shown to reduce symptoms of schizophrenia and also improve metabolic conditions.