From the Guidelines
Olanzapine can increase the risk of developing diabetes or worsen existing diabetes in patients. This antipsychotic medication, commonly used to treat schizophrenia and bipolar disorder, affects glucose metabolism by causing insulin resistance and potentially impairing insulin secretion. Patients taking olanzapine should have their blood glucose levels monitored regularly, especially during the first few months of treatment when the risk is highest, as recommended by the 2024 standards of care in diabetes 1. Warning signs of diabetes development include increased thirst, frequent urination, unexplained weight loss, and fatigue.
If diabetes develops while on olanzapine, healthcare providers may consider switching to an alternative antipsychotic with lower metabolic risk (such as aripiprazole or ziprasidone) if clinically appropriate, as these alternatives tend to have fewer metabolic effects 1. Weight management through diet and exercise is important for patients on olanzapine, as weight gain is common and can further increase diabetes risk. Patients with pre-existing diabetes who require olanzapine may need adjustments to their diabetes medications to maintain glycemic control. The metabolic effects of olanzapine appear to be related to its antagonism of histamine H1 and serotonin 5-HT2C receptors, which affect appetite regulation and metabolic processes.
Key considerations for managing patients on olanzapine include:
- Regular monitoring of blood glucose levels, especially in the first few months of treatment
- Screening for prediabetes or diabetes at baseline, 12-16 weeks after medication initiation, and annually thereafter, as suggested by the 2024 guidelines 1
- Weight management through diet and exercise to mitigate the risk of weight gain and its consequences on diabetes risk
- Potential adjustment of diabetes medications for patients with pre-existing diabetes
- Consideration of alternative antipsychotics with lower metabolic risk if diabetes develops or worsens during olanzapine treatment.
From the FDA Drug Label
Metabolic Changes: Atypical antipsychotic drugs have been associated with metabolic changes including hyperglycemia, dyslipidemia, and weight gain. Hyperglycemia and Diabetes Mellitus: In some cases extreme and associated with ketoacidosis or hyperosmolar coma or death, has been reported in patients taking olanzapine. Patients taking olanzapine should be monitored for symptoms of hyperglycemia and undergo fasting blood glucose testing at the beginning of, and periodically during, treatment.
Olanzapine and Diabetes Risk: Olanzapine has been associated with an increased risk of hyperglycemia and diabetes mellitus. In some cases, this has led to severe complications such as ketoacidosis or hyperosmolar coma, and even death. Therefore, patients taking olanzapine should be closely monitored for symptoms of hyperglycemia and undergo regular fasting blood glucose testing 2.
From the Research
Olanzapine and Diabetes Mellitus
- Olanzapine, an atypical antipsychotic, has been associated with metabolic abnormalities, including weight gain and changes in glucose profiles 3, 4, 5, 6, 7.
- Studies have shown that olanzapine treatment can lead to increased glucose levels, with higher doses being associated with greater glucose increases 3.
- A case report found that a patient with a history of gestational diabetes mellitus developed hyperglycemia after being initiated on olanzapine, highlighting the potential risk of olanzapine-associated hyperglycemia in patients with a history of diabetes 5.
- The underlying mechanisms of olanzapine-induced diabetes mellitus are not fully understood, but may involve the disruption of glucose metabolism through receptor-binding profiles, humoral factors, and transporter proteins 6.
- Predictors of weight gain, which may increase the risk of diabetes mellitus, include age, baseline body mass index, appetite stimulation, previous antipsychotic exposure, and antipsychotic treatment duration 7.
Risk Factors and Monitoring
- Patients receiving olanzapine, particularly those with a history of diabetes or borderline increased blood glucose levels, should be closely monitored for signs of hyperglycemia and weight gain 3, 4, 5.
- Treatment duration and co-prescription of other medications, such as antipsychotics, antidepressants, benzodiazepines, and antihypertensive agents, may also contribute to weight gain and increase the risk of diabetes mellitus 3.
- Regular monitoring of weight, fasting blood glucose, and lipid profiles is recommended for patients taking olanzapine to minimize the risk of metabolic side effects 7.