From the Editor

Beyond diabetes: The beneficial uses of metformin in psychiatry

Current Psychiatry. 2022 March;21(3):7-9 | doi: 10.12788/cp.0225

References

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Metabolic dysregulation is quite common among psychiatric patients, especially those with psychotic or mood disorders. Obesity, diabetes, and dyslipidemia can be present at the onset of the illness, or as an iatrogenic complication. This often leads to premature mortality due to elevated cardiovascular and cerebrovascular risks.

Enter metformin. It is the most widely used hypoglycemic agent for type 2 diabetes (T2D), and it is frequently used by psychiatric clinicians. Discovered in 1922 and developed in France in the 1950s, metformin was approved for use in the United States in 1995, 3 decades after its launch in Europe. Its original trade name in the United States was Glucophage, and it is currently available from several companies in generic form. It is included on the World Health Organization list of essential medications.

T2D is currently an epidemic across the general populations globally, especially in the United States, where approximately 95% of the 37 million individuals with diabetes have been diagnosed with T2D.¹ This is 300% higher than the prevalence in the 1970s. No wonder metformin is one of the most often-used drugs in all of medicine, and a staple in primary care and psychiatry. It has helped countless patients avoid the multisystem hazards of insulin resistance, which is the root cause of T2D.

Metformin exerts its hypoglycemic effects by:

decreasing glucose production from the liver
increasing insulin receptors’ sensitivity in various body tissues
increasing secretion of growth differentiating factor, which reduces appetite and calorie intake.

In 2017, the American College of Physicians updated its guidelines to adopt metformin as the first-line treatment for T2D, especially because the class of sulfonylureas were associated with a more than 5-fold higher risk of severe low blood sugar events compared with metformin.² In addition, metformin causes weight loss, while sulfonylureas are associated with weight gain. Metformin is particularly useful in gestational diabetes, where babies are born with less visceral fat and are less prone to insulin resistance later in life as adults.

The adverse effects of metformin are dose-related and mostly gastrointestinal (GI), including nausea, vomiting, cramps, diarrhea, and flatulence. Gradual titration or using the extended-release formulation can lower or avert GI discomfort. Metformin should not be used in patients with severe kidney or liver disease. With long-term use, metformin can cause malabsorption and eventual deficiency of vitamin B12.

The metabolic benefits of metformin listed below are why psychiatrists use it in clinical practice. However, this medication has several benefits that go beyond metabolic disorders. Clinicians should be aware of all of the following salutary physical and mental effects of metformin.

Metabolic benefits

Decreasing glucose dysregulation with the use of clozapine and other antipsychotics.³
Decreasing weight, body mass index, and waist circumference with the use of clozapine.⁴
Decreasing triglycerides and total cholesterol.⁵
Mitigating clozapine-induced obesity, especially if used prophylactically.⁶
Lowering antipsychotic-induced weight gain.⁷

Continue on to: Nonmetabolic benefits...