Correlation of serum ghrelin levels with body mass index and carbohydrate metabolism in patients treated with atypical antipsychotics

The prevalence of diabetes mellitus and metabolic syndrome is higher in patients with schizophrenia than in the normal population. Atypical antipsychotic drugs are used in psychiatry since the beginning of 1990. These drugs differ from the “typical” antipsychotics used previously, as they have less extrapyramidal side effects, and because of this they are tolerated better, but are associated with weight-gain and disturbances in carbohydrate metabolism. Ghrelin is an orexigen hormone partaking in body weight regulation. It is produced in the enteroendocrine P/D1 cells of the gastric mucosa and secreted to the circulation. The aim of our study was to determine ghrelin levels of atypical antipsychotic-treated patients in relationship with their body mass index (BMI) and carbohydrate metabolism. We measured the fasting serum ghrelin levels in 56 patients (male/female: 16/40, age mean ± S.D.: 50.6 ± 5.6 years) treated with atypical antipsychotics (clozapine, olanzapine, risperidon and quetiapine), and in 75 healthy control subjects, age and gender matched (RIA Linco, USA) in relationship with their BMI and their fasting and 75 g OGTT 120 min blood glucose values. The serum ghrelin levels of the patient group were notably higher (1333 ± 659 pg/ml) than in the control group (368 ± 103, p < 0.0001; Mann-Whitney). We found no difference among the four antipsychotics in weight-gain, diabetes prevalence and the serum ghrelin levels. The BMI of the patient group was significantly higher (29.3 ± 7.2 kg/m2 versus 24.3 ± 3.7 kg/m2, p < 0.0001; Mann-Whitney); 32% of them had blood glucose abnormality (18/56). There was no difference between the ghrelin levels in diabetic and non-diabetic patients. We found a significant negative linear correlation between the serum ghrelin and BMI (r = −0.35, p = 0.0078; Spearman), the ghrelin and fasting blood glucose (r = −0.32, p = 0.015) and OGTT 75 g 120 min blood glucose levels (r = −0.27, p = 0.036). The orexigen effect of elevated serum ghrelin levels can contribute to the weight-gain and high diabetes prevalence associated with atypical antipsychotic treatment. The link between atypical antipsychotic treatment and elevated serum ghrelin levels is unknown so far, but a dysregulation of the central feedback mechanism can be hypothesised.