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Somatic mutations in the alpha-chain (alpha s) of the stimulatory regulatory protein of adenylyl cyclase (Gs) causing constitutive activation of the enzyme have been identified in a subset of human GH-secreting pituitary adenomas. This study reports on the differences between acromegalic patients bearing tumors without (group 1; n = 51) or with (group 2; n = 29) this alteration. No difference in age, sex, clinical features, duration of the disease, or cure rate was observed between the two groups. By contrast, group 2 patients had higher basal GH levels than group 1. Moreover, a significant difference in sellar morphology was found; group 2 patients more frequently showed sellas of normal size (grade I) than group 1. Hypersecretory activity of group 2 tumors was also apparent at electron microscopy; contrary to those of group 1, cells of group 2 tumors were densely granulated and showed prominent rough endoplasmic reticulum and Golgi complex. With respect to group 1, group 2 patients were less responsive to GH-releasing hormone, while they were more sensitive to somatostatin- and dopamine-induced GH inhibition. These results suggest that patients with constitutively active adenylyl cyclase have hyperactive tumors; the sensitivity of these tumors to inhibitory agents (somatostatin and dopamine), possibly counteracting the expression of activating mutations, might explain the low rate of tumor growth.

OBJECTIVE -The presence of an enhanced cortisol secretion in patients with type 2 diabetes is debated. In type 2 diabetic subjects, cortisol secretion was found to be associated with the complications and metabolic control of diabetes. We evaluated cortisol secretion in 170 type 2 diabetic subjects and in 71 sex-, age-, and BMI-matched nondiabetic subjects. RESEARCH DESIGN AND METHODS-In all subjects, we evaluated ACTH at 8:00 A.M. in basal conditions and serum cortisol levels at 12:00 P.M. (F24) and at 9:00 A.M. after a 1-mg overnight dexamethasone suppression test and 24-h urinary free cortisol (UFC). In diabetic patients, we evaluated the presence of chronic complications (incipient nephropathy, asymptomatic neuropathy, background retinopathy, and silent macroangiopathy). Patients were subdivided according to the absence (group 1, n ϭ 53) or presence (group 2, n ϭ 117) of diabetes complications.RESULTS -In group 2, UFC (125.2 Ϯ 4.6 nmol/24 h) and F24 (120.6 Ϯ 4.1 nmol/l) were higher than in group 1 (109.2 Ϯ 6.8 nmol/24 h, P ϭ 0.057, and 99.7 Ϯ 6.1 nmol/l, P ϭ 0.005, respectively) and in nondiabetic patients (101.7 Ϯ 5.9 nmol/24 h, P ϭ 0.002, and 100.3 Ϯ 5.3 nmol/l, P ϭ 0.003, respectively). In diabetic patients, the number of complications was associated with F24 (R ϭ 0.345; P Ͻ 0.0001) and diabetes duration (R ϭ 0.39; P Ͻ 0.0001). Logistic regression analysis showed that the presence of diabetes complications was significantly associated with F24, sex, duration of diabetes, and glycated hemoglobin.CONCLUSIONS -In type 2 diabetic subjects, hypothalmic-pituitary-adrenal activity is enhanced in patients with diabetes complications and the degree of cortisol secretion is related to the presence and number of diabetes complications. Diabetes Care 30:83-88, 2007I n patients with type 2 diabetes, glucocorticoid secretion has been suggested to be a possible link between insulin resistance and the features of the metabolic syndrome (hypertension, obesity, coronary heart disease, hyperlipidemia, and type 2 diabetes) (1-4). In fact, while glucocorticoid excess (overt or subclinical) has been demonstrated to lead to diabetes or to worsen metabolic control (5-7), the relationship between cortisol levels, insulin resistance, and chronic complications in type 2 diabetic patients without hypercortisolism is still a matter of debate.In past years, the hypothalamicpituitary-adrenal (HPA) axis secretion in patients with type 2 diabetes has been extensively investigated (8 -14). In particular, some studies reported in these subjects an elevation of ACTH (10,12), basal (9 -11) and after dexamethasone test serum cortisol (13,14), and late-night salivary cortisol levels (15). In contrast, other previous studies (16 -17) did not show any alteration of pituitary-adrenal axis secretion. The presence of chronic complications of type 2 diabetes (i.e., macroangiopathy, retinopathy, and neuropathy) has been associated to with HPA axis activity (9,18 -23), and an association between the degree of severity of several clinical measures of d...