Problems with regulation of blood sugar may appear in the very earliest stages of schizophrenia, according to a review of research published January 11th 2017 in JAMA Psychiatry. This finding suggests people with schizophrenia should be monitored for type 2 diabetes from the onset of illness.

Past research has shown that people with schizophrenia have higher risk of developing type 2 diabetes. Type 2 diabetes is a progressive disease in which the body either can't use its own insulin efficiently or doesn't make enough insulin, a hormone that regulates how the body absorbs sugar to use for fuel. As a result, blood sugar rises to higher than normal levels.

The team led by Oliver Howes, Ph.D., of Imperial College London in the UK and a 2013 NARSAD Independent Investigator grantee, and the paper’s first author, Toby Pillinger, MRCP, aggregated the results of many previous studies to examine whether individuals already show a change in blood sugar regulation at the time of their first episode of schizophrenia, before getting started on antipsychotic treatment.

The results of this “meta-analysis” were based on 16 studies that reported blood sugar and insulin levels in both people with first-episode schizophrenia and controls. Overall, the studies included 731 patients and 614 controls.

The results revealed that people with first-episode schizophrenia already showed evidence of problems in regulating sugar. Blood sugar levels, insulin levels and insulin resistance were all significantly elevated in patients compared with controls, the researchers found.

The reason for this difference is not clear. Many factors, ranging from lifestyle habits to a shared genetic vulnerability to both type 2 diabetes and schizophrenia, may be involved.

Regardless of the mechanism, the findings suggest that people with schizophrenia are at higher risk for developing diabetes and should be educated about preventive measures such as diet and exercising. Since some antipsychotic medications may further impair sugar regulation, clinicians may want to consider using medications with lower associated diabetic risk in order to reduce the impact of treatment, the researchers say.