MedicalResearch.com Interview with:
Dr. Toby Pillinger
Dr Toby Pillinger MA(Oxon) BM BCh MRCP
Institute of Psychiatry, Psychology and Neuroscience
King’s College London
MedicalResearch.com: What is the background for this study? What are the main findings?
Response: Our meta-analysis has provided strong evidence that compared with healthy controls, individuals with early schizophrenia are at increased risk of developing type 2 diabetes mellitus, even when the effects of antipsychotic drugs, diet and exercise are taken out of the equation.
Schizophrenia is associated with a dramatically reduced life expectancy, with individuals dying up to 30 years earlier than the general population. Approximately 60% of this excess mortality is due to physical health disorders such as heart attack or stroke, for which diabetes is a major risk factor.
People with long-term schizophrenia are 3 times more likely than the general population to have diabetes, something that has previously been blamed on poor diet and exercise habits, as well as the use of antipsychotic medication. However, the link between schizophrenia and diabetes was first made back in the 19th century, long before the use of antipsychotics, and in an era where diets were less likely to cause diabetes. This could suggest that there is a causative link between schizophrenia and diabetes.
Our meta-analysis examined whether diabetes risk is already raised in people at the onset of schizophrenia, before antipsychotics have been prescribed and before a prolonged period of illness that may be associated with poor diet and sedentary behaviour. We pooled data from 16 studies comprising 731 patients and 614 individuals from the general population. We collated blood data examining fasting blood glucose levels, blood glucose levels following the oral glucose tolerance test, fasting insulin levels and degree of insulin resistance.
We demonstrated that compared with healthy controls, individuals with early schizophrenia had raised fasting glucose, raised levels of glucose following the oral glucose tolerance test, raised fasting insulin and elevated insulin resistance. Furthermore, these results remained statistically significant even when we restricted our analyses to studies where individuals with schizophrenia were matched to healthy controls with regards their diet, the amount of exercise they engaged in and their ethnic background.
This suggests that our results were not wholly driven by differences in lifestyle factors or ethnicity between the two groups, and may therefore point towards a direct role for schizophrenia in increasing risk of diabetes.