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Atypical antipsychotics, weight gain and type 2 diabetes |
Weight management and diabetes prevention is a major issue for the general population but people with psychiatric disorders often face even greater challenges due to the medications prescribed and other lifestyle factors. It is usually up to the patient’s GP to manage the weight problem and co-morbidities.
Evidence is very strong that obesity is more prevalent among people with schizophrenia and bipolar disorder and atypical antipsychotics are often implicated. Compliance with the medication may be jeopardised because of this side effect and early intervention with lifestyle measures such as nutritional advice and increased levels of physical activity to prevent weight gain may be helpful.
As regards diabetes, although it is tempting to think that the increased rates of people on a typical antipsychotics is due purely to weight gain, patients can develop diabetes without significant weight gain. Diabetes usually improves rapidly when the antipsychotic is withdrawn.
The mechanisms leading to diabetes can include the drug induced weight gain, but there is also evidence of a direct metabolic effect. This may be related to antagonism at the 5-(HT.sub2c) or histamine (H.sub.1) receptors or to an elevation of serum leptin beyond that induced by increased body weight alone. (1)
Atypical antipsychotics are a great advance in management of psychiatric diseases and are now commonly prescribed. GPs are well placed to monitor weight and the metabolic state of their psychiatric patients and should be alert to these side effects and intervene with lifestyle change advice where possible.
Some antipsychotics are more prone to produce obesity and diabetes than others. Given the compounding effects of weight gain and diabetes on coronary heart disease (the major cause of premature death in schizophrenia), aggravated by smoking and inactivity (frequent features of schizophrenia), antipsychotics with lower potential for weight gain and diabetes may be preferred but this may take second priority to effectiveness in controlling psychiatric symptoms.
Patients on clozapine (Clozaril) and olanzapine (Zyprexa) should be particularly closely monitored. Quetiapine (Seroquel) and risperidone (Risperdal) may be slightly less prone to produce weight gain but should still be carefully monitored for weight gain, blood sugars and other cardiovascular risk factors. Newer agents aripiprazole (Abilify) and ziprasidone (the latter not yet released in Australia) may be superior for lack of weight gain and hyperglycaemia but long term data is as yet unavailable.
All patients on these medications should be regularly monitored for weight, waist circumference, blood pressure, fasting plasma glucose and fasting lipid profile.
One of the advantages of the atypical antipsychotics over the older typical agents is lack of extrapyramidal side effects, tardive dyskinesia and anticholiergic side effects. However weight gain and diabetes are significant problems that GPs will encounter. Psychiatrists and GPs need to work together not only to manage the mental state of these patients but to also monitor their overall metabolic and cardiovascular health.
Bearing in mind how often atypical antipsychotics are used, ways of dealing with obesity and diabetes prevention for often disadvantaged mental health patients in our region is a high priority. This needs to be further researched to look for ways to better monitor and manage these challenging health issues.
(1) Diabetes Care: May 2003. Patients on atypical antipsychotics drugs:another high-risk group for type 2 diabetes. Michael E.J. Lean
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