Patients with schizophrenia may be at an elevated risk of developing diabetes, new research shows. The study, recently published in JAMA Psychiatry, uncovered a direct link between the mental disorder and diabetes, regardless of diabetes risk factors.
Estimated rates of type 2 diabetes in this population are 3 times higher than in individuals without schizophrenia, which has previously been attributed to the use of antipsychotic medication along with poor diet and lack of exercise.  
Researchers in England set out to determine whether the risk of diabetes development was present at the onset of schizophrenia, as opposed to after a period of time with the illness.
They concluded that fasting plasma glucose levels were elevated in patients with first-episode psychosis (FEP), and that at schizophrenia’s onset, glucose tolerance was reduced, fasting plasma insulin levels elevated, and insulin resistance increased. These results were apparent even in the absence of diabetes risk factors such as antipsychotic use, diet, and exercise.
An analysis of data from 16 case-control studies included a sample of 731 patients and 614 healthy control individuals, and researchers aimed to examine glucose homeostasis in patients with FEP compared to the control group. Blood tests indicated that fasting plasma glucose levels and plasma glucose levels were significantly increased in patients with FEP.
The study acknowledged several shared risk factors related to both conditions, such as genetic risk and developmental risk factors, as well as stress related to developing schizophrenia. Researchers concluded that initiating diabetes prevention strategies at the onset of schizophrenia diagnosis is important, and should be considered when determining appropriate antipsychotic medications and counseling patients on lifestyle modifications.
Pillinger T, Beck K, Gobjila C. Impaired glucose homeostasis in first-episode schizophrenia: A systematic review and meta-analysis. JAMA Psychiatry. 2017; doi:10.1001/jamapsychiatry.2016.3803.