A study of central serotoninergic activity in healthy subjects and patients with Type 2 diabetes treated by traditional one-to-one care or Group Care

AIM: Central serotoninergic activity may modulate glucose metabolism via neuroendocrine effectors. Group Care is a clinico-pedagogic intervention that improves metabolic control and quality of life in Type 2 diabetes through lifestyle modification and, possibly, central mechanisms. The hypothesis that central serotoninergic activity is modified in patients followed by Group Care was tested by measuring their hypothalamic- pituitary-adrenal response to citalopram, a selective serotonin reuptake inhibitor. METHODS AND SUBJECTS: Ten healthy controls and 17 non-obese, non-insulin-treated patients with Type 2 diabetes received, in random order, iv infusions of either 20 mg citalopram or saline. Nine patients had been longterm on Group Care and 8 had always been on traditional one-to-one care. Circulating glucose, insulin, ACTH, cortisol, DHEA, GH and PRL were measured every 15 min for 240 min. Differences between areas under the curves after citalopram and saline (Δ-AUC) were calculated. RESULTS: Citalopram stimulated ACTH and cortisol secretion in healthy subjects (p=0.026 and p=0.011, respectively) and patients on Group Care (p=0.056 and p=0.038) but not in patients on traditional care. In healthy subjects, basal glucose correlated with growth hormone Δ- AUC (r=0.820; p=0.004) and inversely with insulin Δ-AUC (r=-0.822; p=0.003). The former correlation was preserved in the patients (r=0.637; p=0.026). CONCLUSIONS: Diabetes may blunt the response of the hypothalamic-pituitary-adrenal axis to citalopram, but this is preserved in patients followed by a long-term intervention model that improves clinical as well as cognitive and emotional variables.