While the metabolic risks associated with antipsychotic medications use are now well known, finding some actual numbers about the risk have been slow to come. A recent study by Nielsen and colleagues published in the Journal of the American Academy of Child and Adolescent Psychiatry offers some specific numbers that can be used when discussing the potential risk of developing Type 2 Diabetes in the course of treatment with antipsychotic medication.
To arrive at these numbers, a case-control design was used that obtained information from a large Danish registry of psychiatric patients under 18 years of age seen from 1999 to 2010. The indicator of having Type 2 Diabetes was the prescribing on an oral antidiabetic medication comparing between those who were and were not also prescribed an antipsychotic medication. Antipsychotic use was counted as positive if one or more prescriptions were filled. Regression analyses were used, controlling for age, sex, and diagnosis in order to assess for the possibility that the diagnosis, rather than the treatment, might be behind any increase in diabetes. The records of nearly 50,000 psychiatrically ill youth were examined.
Overall, the rate of Type 2 Diabetes among youth treated with antipsychotics was 0.72% compared to a rate of 0.27% in psychiatrically ill youth not given antipsychotic medication. This difference, when controlling for potential confounds, resulted in a significantly elevated odds ratio of 1.60. Being female and being older at the time of diagnosis was also related to diabetes. When metformin was excluded as an indicator of diabetes (because of the possibility that it was being used in many cases to treat wait gain and protect against the development of diabetes), the odds ratio related to antipsychotic use went up to 3.71; however, this odds ratio was no longer significant due to such a small number of cases. (The authors state in the discussion that metformin is rarely used in Denmark for weight control). Overall, the number needed to harm was calculated at 224.
The authors concluded that antipsychotic medication use does increase the risk of developing Type 2 Diabetes. In the Discussion section, they recommend close adherence to indication and metabolic monitoring guidelines.
It is nice to have some specific numbers to talk about when having discussion of potential side effects that don’t rely on small and short-term clinical trials. At the same time, however, these kinds of large registry databases can struggle with measuring other factors that may be important, such as compliance with treatment and overall duration. If milder diabetes was diagnosed but controlled through nonpharmacological means, for example, this study would have misclassified these children.
It will also be interesting to see how this Diabetes risk will be interpreted. An 60% increase sounds like a lot, yet the overall rate was 0.72% which is likely lower than many people were expecting. Several of the authors have rather extensive ties to various pharmaceutical companies, which will likely cause some people to discount the results. As far as I can see, the study has not received much press at all, perhaps because the results were not that dramatic in either direction.
Reference
Nielsen RE, et al. Risk of Diabetes in Children and Adolescents Exposed to Antipsychotics: A Nationwide 12-Year Case-Control Study. JAACAP. 53(9):971–979, 2014.