Taking Antipsychotics? Diabetes Risk Runs High In First Few Months, Study Warns

FRIDAY, Oct. 16, 2026 (HealthDay News) — People starting antipsychotics need to closely track their weight and blood sugar for the first few months to avoid developing type 2 diabetes, a new study says.

Second-generation antipsychotics are known to increase the risk of diabetes and weight gain, but the most significant metabolic changes in patients tend to occur within three months, the research team found.

The findings were published Oct. 14 in The Lancet Psychiatry.

“Our study shows that the first 90 days after starting treatment are a key period when changes linked to diabetes and weight gain can begin,” lead researcher Juan Carlos Bazo-Alvarez, a senior research fellow with University College London, said in a news release.

“With this information in mind, healthcare professionals should check both weight and blood sugar before treatment starts and again during the first few months afterwards,” Bazo-Alvarez said.

For the new study, researchers analyzed data from nearly 97,000 adults in England who’d started taking an antipsychotic between 2000 and 2023. The drugs in question included olanzapine, quetiapine, risperidone or aripiprazole.

Results showed that average blood sugar rose about 14 times faster and weight about nine times faster during the first 90 days of treatment than before starting medication.

Of the four drugs, olanzapine showed the largest early increases in both blood sugar and weight, which rose about 50 times faster and 10 times faster, respectively.

People with prediabetes also appeared to have a greater risk from the drugs. About 19% of people with prediabetes wound up with type 2 diabetes within two years of starting antipsychotics, compared with 3% of those with normal blood sugar levels.

Women also were disproportionately affected.

Blood sugar rose about 24 times faster in women during the first 90 days, compared with 10 times faster in men. Likewise, weight gain was 12 times faster for women and 10 times faster for men.

“By checking blood sugar and weight early, doctors may be able to spot problems sooner and offer support, advice, or treatment to help prevent more serious health issues later on,” Bazo-Alvarez said. “Our findings may also help clinicians to pay particular attention to certain groups who may be more at risk."

More information

The Cleveland Clinic has more on antipsychotic medications.

SOURCE: University College London, news release, Oct. 14, 2026