Clinical inertia and its impact on treatment intensification in people with type 2 diabetes mellitus

Many people with type 2 diabetes mellitus (T2DM) fail to achieve glycaemic control promptly after diagnosis and do not receive timely treatment intensification. This may be in part due to 'clinical inertia', defined as the failure of healthcare providers to initiate or intensify therapy when indicated. Physician-, patient- and healthcare-system-related factors all contribute to clinical inertia. However, decisions that appear to be clinical inertia may, in fact, be only 'apparent' clinical inertia and may reflect good clinical practice on behalf of the physician for a specific patient. Delay in treatment intensification can happen at all stages of treatment for people with T2DM, including prescription of lifestyle changes after diagnosis, introduction of pharmacological therapy, use of combination therapy where needed and initiation of insulin. Clinical inertia may contribute to people with T2DM living with suboptimal glycaemic control for many years, with dramatic consequences for the patient in terms of quality of life, morbidity and mortality, and for public health because of the huge costs associated with uncontrolled T2DM. Because multiple factors can lead to clinical inertia, potential solutions most likely require a combination of approaches involving fundamental changes in medical care. These could include the adoption of a person-centred model of care to account for the complex considerations influencing treatment decisions by patients and physicians. Better patient education about the progressive nature of T2DM and the risks inherent in long-term poor glycaemic control may also reinforce the need for regular treatment reviews, with intensification when required.

Personalized intensification of insulin therapy in type 2 diabetes - does a basal-bolus regimen suit all patients?

Many patients with type 2 diabetes mellitus (T2DM) require insulin therapy. If basal insulin fails to achieve glycemic control, insulin intensification is one possible treatment intensification strategy. We summarized clinical data from randomized clinical trials designed to compare the efficacy and safety of basal-bolus and premixed insulin intensification regimens. We defined a between-group difference of ≥0.3% in end-of-study glycated hemoglobin (HbA1c) as clinically meaningful. A PubMed database search supplemented by author-identified papers yielded 15 trials which met selection criteria: randomized design, patients with T2DM receiving basal-bolus (bolus injection ≤3 times/day) vs. premixed (≤3 injections/day) insulin regimens, primary/major endpoint(s) HbA1c- and/or hypoglycemia-related, and trial duration ≥12 weeks. Glycemic control improved with both basal-bolus and premixed insulin regimens with - in most cases - acceptable levels of weight gain and hypoglycemia. A clinically meaningful difference between regimens in glycemic control was recorded in only four comparisons, all of which favored basal-bolus therapy. The incidence of hypoglycemia was significantly different between regimens in only three comparisons, one of which favored premixed insulin and two basal-bolus therapy. Of the four trials that reported a significant difference between regimens in bodyweight change, two favored basal-bolus therapy and two favored premixed insulin. Thus, on a population level, neither basal-bolus therapy nor premixed insulin showed a consistent advantage in terms of glycemic control, hypoglycemic risk, or bodyweight gain. It is therefore recommended that clinicians should adopt an individualized approach to insulin intensification - taking into account the benefits and risks of each treatment approach and the attitude and preferences of each patient - in the knowledge that both basal-bolus and premixed regimens may be successful.

Exenatide: a review from pharmacology to clinical practice

BACKGROUND

Exenatide is an incretin mimetic that activates glucagon-like-peptide-1 receptors. It blunts the postprandial rise of plasma glucose by increasing glucose-dependent insulin secretion, suppressing inappropriately high glucagon secretion and delaying gastric emptying.

METHODS

In seven clinical trials performed in 2845 adult patients with type 2 diabetes mellitus who were inadequately controlled by a sulphonylurea and/or metformin (glycosylated haemoglobin, HbA1c <or=11%), or by thiazolidinediones (with or without metformin) and treated for periods from 16 weeks to 3 years, exenatide (5 microg b.i.d. s.c. for the first 4 weeks of treatment and 10 microg b.i.d. s.c. thereafter) reduced HbA1c, fasting and postprandial glucose, and body weight dose dependently, and was similar to insulin glargine and biphasic insulin aspart in reducing HbA1c. Body weight diminished with exenatide, whereas it increased with both insulin preparations. Positive effects on the lipid profile and a reduction in C-reactive protein were also recorded with exenatide. Treatment extensions up to 3 years showed that benefits were maintained in the long term. Adverse events were usually mild to moderate in intensity, and generally the frequency decreased with continued therapy. The most common was nausea (whose incidence may be reduced by gradual dose escalation from 5 microg b.i.d. to 10 microg b.i.d.), vomiting, diarrhoea, headache and hypoglycaemia (almost exclusively in patients treated with a sulphonylurea).

RESULTS AND CONCLUSIONS

Exenatide is a new, promising therapeutic option for type 2 diabetic patients inadequately controlled by oral agents, before insulin therapy, offering the added benefits of body weight reduction and tight postprandial glucose control.

Osteoporosis treatment and fracture incidence: the ICARO longitudinal study

None of the available osteoporosis therapies completely abolish the risk of fracture. Among 862 patients on treatment with antiresorptive agents (alendronate, risedronate, and raloxifene) for >1 year a fragility fracture was observed in 9.5%/year. This incidence is considerably higher than that observed in randomized clinical trials.

INTRODUCTION

Available osteoporosis therapies reduced in randomized controlled trials (RCTs) the risk of fracture by 30-50%. The proportion of patients suffering from new fractures while on active treatment ("inadequate clinical treatment response" or ICR) can be derived from the data of the RCTs, where confounding factors are usually controlled by the exclusion criteria. In the retrospective part of the ICARO study we observed a 8.9% annual incidence of ICR. Here we report the results of the longitudinal part of the study.

METHODS

The study includes 862 women with severe postmenopausal osteoporosis. Ninety-two of these patients (10.7%) were defined as having ICR (9.5%/year) during therapy with antiresorptive drugs (alendronate, risedronate, and raloxifene) for at least 1 year.

RESULTS

The ICR patients were comparable to patients who did not sustain clinical fractures with regard to body mass index, follow-up duration, number of prevalent vertebral fractures, type of osteoporosis treatment, proportion of patients taking calcium and vitamin D supplements, and compliance with treatment. Those with ICR were significantly older (p=0.032) and more frequently had multiple vertebral deformities (p=0.013).

CONCLUSIONS

The incidence of ICR during treatment with antiresorptive agents among patients with severe postmenopausal osteoporosis in a routine setting is considerably higher than that observed in randomized clinical trials.

Unmet needs among patients with type 2 diabetes and secondary failure to oral anti-diabetic agents

Secondary failure is defined as a deterioration of glucose control in patients with Type 2 diabetes on oral antidiabetic drugs (OAD), mainly due to the progressive decline in beta-cell function and reduction in insulin secretion. The consequent hyperglycemia is the most important determinant for the development of microvascular and macrovascular complications, so that an early recognition of this phenomenon can improve long-term outcomes. The recent lowering of target glycosylated hemoglobin (HbA1c) levels by international guidelines not only emphasises the importance of tight glycemic control, but also means that secondary failure to OAD will occur much sooner and is almost unavoidable. Accordingly, in the last years, new different therapeutic strategies were explored to improve the treatment of this condition. The aim of this review is to examine current approaches for treating patients with secondary failure, barriers to achieving and maintaining glycemic control, and recent evidence for emerging therapies which may represent a valid therapeutic option in subjects failing on oral hypoglycemic agents by acting mainly, but not only, at a beta-cell level. In particular, we will focus on the co-administration of OAD plus a novel drug class known as incretin mimetics (e.g. exenatide and liraglutide), which target insulin secretion, and on thiazolidinediones, which act on insulin resistance. Only incretin-mimetics have a lowering HbA1c action, due to the improvement in beta-cell function, which is coupled to significant weight loss. Even if these new options seem to improve the outcome of secondary failure, further investigation is needed to confirm positive results in the long term.

Outcome of pregnancy in type 1 diabetic patients treated with insulin lispro or regular insulin: an Italian experience

Some studies have shown that fetal outcome observed in patients using insulin lispro is much the same as in pregnant women using regular insulin. This study aims to analyze the Italian data emerging from a multinational, multicenter, retrospective study on mothers with type 1 diabetes mellitus before pregnancy, comparing those treated with insulin lispro for at least 3 months before and 3 months after conception with those treated with regular insulin. The data collected on pregnant women with diabetes attending 15 Italian centers from 1998 to 2001 included: HbA1c at conception and during the first and third trimesters, frequency of severe hypoglycemic episodes, spontaneous abortions, mode and time of delivery, fetal malformations and mortality. Seventy-two diabetic pregnancies treated with lispro and 298 treated with regular insulin were analyzed, revealing a trend towards fewer hypoglycemic episodes in the former, who also had a significantly greater reduction in HbA1c during the first trimester. The rate of congenital malformations was similar in the offspring of the two groups of women treated with insulin lispro or regular insulin. These findings suggest that insulin lispro could be useful for the treatment of hyperglycemia in type 1 diabetic pregnant women.

GH and IGF-I as therapeutic agents for osteoporosis

Current strategies for the treatment of osteoporosis rely almost exclusively on agents whose pharmacological actions are primarily antiresorptive. There is, therefore, growing interest in developing agents able to stimulate bone formation, such as GH and IGF-I, which play an important role in bone metabolism, being essential for the development and growth of the skeleton and for the maintenance of bone mass. Furthermore, the decline in GH/IGF-I axis with aging, is correlated with the increased risk of osteoporosis and fragility fractures in elderly population. Several studies investigated the potential of GH and/or IGF-I as therapeutic agents in osteoporotic patients (post-menopausal women and idiopathic osteoporotic men), showing a clear correlation between the used GH dosage (and the obtained IGF-I plasmatic levels) and the increase in bone turnover markers and/or bone mineral density (BMD) at different skeletal sites. In particular, the use of IGF-I/IGFBP-3 complex seems to be very useful and safe in older women with recent hip fracture. Also the possibility of combining GH/IGF-I treatment with antiresorptive drugs (such as calcitonin and alendronate) has been explored, showing controversial results on BMD at different skeletal sites. In summary, based on the current evidence, it is clear that circulating GH and IGF-I are critical for skeletal modeling, bone acquisition and age related bone loss. Nevertheless, controlled studies with fracture incidence as endpoints are needed to fully assess the potential of these bone anabolic agents in the treatment of osteoporosis.

Growth hormone secretion and leptin in morbid obesity before and after biliopancreatic diversion: relationships with insulin and body composition

Obesity is characterized by increased leptin levels and insulin resistance, whereas blunted GH secretion is paired with normal, low, or high plasma IGF-I levels. To investigate body composition in human obesity and the interactions among the GH-IGF-I axis, leptin, and insulin resistance [measured with the homeostasis model assessment (HOMA) score], we studied 15 obese females, aged 23-54 yr (mean age, 42.7 +/- 2.6), with a body mass index (BMI) of 44.02 +/- 1.45 kg/m(2), who underwent treatment by biliopancreatic diversion (BPD), before and after surgery (16-24 months; BMI, 28.29 +/- 0.89 kg/m(2)). Our controls were 15 normal females, aged 28-54 yr (mean age, 40.8 +/- 2.3 yr), with a BMI of 27.52 +/- 0.53 kg/m(2). Insulin and leptin levels and HOMA scores were higher pre-BPD than in the controls. The GH response to GHRH was blunted, with a GH peak and GH area under the curve (AUC) significantly lower than those in controls. IGF-I and IGF-binding protein-3 (IGFBP-3) were also lower than control values. After surgery, BMI, fat mass, lean body mass, HOMA, insulin, and leptin significantly decreased. Furthermore, the GH response to GHRH severely increased; IGF-I and IGFBP-3 levels did not significantly vary. Considering all subjects, correlation analysis showed a strong positive correlation between insulin and leptin, and a negative correlation between insulin and GH peak and between insulin and GH AUC. Regression analysis performed grouping pre- and post-BPD indicated that leptin and GH peak or AUC could best be predicted from insulin levels. The surgical treatment of severe obesity after stabilization of body weight decreases BMI and fat mass while preserving normal lean body mass as well as positively influencing insulin sensitivity and thus aiding the normalization of leptin levels. The insulin reduction may be mainly involved in the increase in the GH response to GHRH through various possible central and peripheral mechanisms while decreasing the peripheral sensitivity to GH itself, as shown by the stable nature of the IGF-I and IGFBP-3 values. Our findings suggest that the changes in insulin levels are the starting point for changes in both leptin levels and the somatotrope axis after BPD.

Preoperative growth hormone response to thyrotropin-releasing hormone and oral glucose tolerance test in acromegaly: a retrospective evaluation of 50 patients

The objective of this study was to investigate the relationship between growth hormone (GH) dynamic tests (thyrotropin-releasing hormone [TRH] test and oral glucose tolerance test [OGTT]), insulin-like growth factor-I (IGF-I) plasma values, tumor size, and clinical outcome in patients with GH-secreting pituitary adenomas. Furthermore, we investigated the potential prognostic utility of the above biochemical parameters in the follow-up of patients with acromegaly. We studied 50 acromegalic patients (18 males and 32 females; mean age, 40 years; range, 16 to 69) who underwent trans-sphenoidal removal of a GH-secreting pituitary adenoma from 1990 to 1994. Preoperatively, we evaluated (1) GH plasmatic levels after an oral glucose load (OGTT) (blood samples were drawn at -15, 0, 30, 60, 90, 120, 150, and 180 minutes after oral administration of 0.75 g/kg body weight [BW] of glucose), (2) GH plasma levels after a TRH test (200 microg as an intravenous [IV] bolus), and (3) basal IGF-I plasma levels after an overnight fast. From 3 to 12 months after surgery we evaluated (1) GH plasma values after an OGTT, and (2) basal plasma IGF-I, free triiodothyronine (FT(3)), free thyroxine (FT(4)), thyroid-stimulating hormone (TSH), and urinary free cortisol. The same tests were performed every year for 5 years. All of the patients were classified into 4 subgroups according to the system of Hardy and Vezina. Preoperatively, "controlled" patients (n = 29) had a GH paradoxical response to TRH (n = 28) and an unresponsiveness to OGTT (n = 29); 23 of them belonged to the I and II classes. Only 5 poorly controlled patients (n = 21) showed a preoperative paradoxical response to TRH and 9 had a preoperative GH partial inhibition after OGTT; 19 of them belonged to the III and IV classes. Our data suggest that in the preoperative period in acromegalic patients the simultaneous presence of a GH paradoxical response to TRH and lack of GH inhibition after OGTT is inversely related to the tumor size and therefore more likely to be restored to normal by surgical treatment.

Opioid dysregulation after biliopancreatic diversion: effect of naloxone on preprandial and postprandial growth hormone (GH)-releasing hormone-induced GH release in surgically induced weight loss

Previously, we have shown that in the opposite extremes of nutritional status (obesity and anorexia nervosa [AN]), the growth hormone (GH) response to GH-releasing hormone (GHRH) is not inhibited by the ingestion of a normal 800-kcal meal at noon. In obese subjects, GHRH-induced GH release is significantly increased (known as the "paradoxical response"). An opiate antagonist infusion (naloxone [NAL]) inhibited this postprandial meal-induced augmenting effect in obese subjects, suggesting opioid involvement in the paradoxical response. The paradoxical postprandial GH release persisted in obese subjects, who after biliopancreatic diversion (BPD) experienced a reduction in body weight, despite the elevation of fasting GH levels. We therefore tested a group of patients, before and after BPD, composed of 10 females, aged 23 to 54 years, who after surgery had experienced a significant reduction in body weight (mean body mass index [BMI], 25.78 +/- 1.01 kg/mg v 44.68 +/- 1.73 kg/mg). The subjects were studied 16 to 24 months after operation, in a phase of stabilized body weight. They underwent, in randomized order, the following tests: GHRH (1 microg/kg as an intravenous [IV] bolus) at 1:00 PM, in the fasting state; GHRH (1 microg/kg) at 1:00 PM, 45 minutes after a standard 800-kcal meal consumed between noon and 12:15 PM; and fasting state and postprandial GHRH (1 microg/kg) during NAL infusion (1.6 mg/h x 2.5 h, starting at noon). We found that NAL inhibited the paradoxical postprandial GH increase only in pre-BPD subjects (GH area under the concentration time curve [AUC] in microg/L/90 min)-before meal: after GHRH 237.54 +/- 62.28, after NAL + GHRH 699.2 +/- 271.57; after meal: after GHRH 575.46 +/- 109.68, after NAL + GHRH 156.17 +/- 24.96. On the other hand, NAL failed to have significant effects in post-BPD subjects (GH AUC in microg/L/90 min)-before meal: after GHRH 871.11 +/- 256.38, after NAL + GHRH 449.19 +/- 119.13; after meal: after GHRH 1,981.54 +/- 319.92, after NAL + GHRH 1,665.91 +/- 315.4. It could be hypothesized that the opioid system is radically modified by the surgical procedure, and that opioids are not the only mediators in the paradoxical response, which persists after BPD, despite the reversion of the hyposecretory GH state, which is a characteristic of obese subjects.

Role of food intake in the modulation of hexarelin-induced growth hormone release in normal human subjects

Hexarelin (HEX) is a new synthetic analog of the Growth Hormone releasing peptides and is stronger than GHRH in releasing GH in vivo. No information is available on the effect of food ingestion on HEX-induced GH secretion. On the other hand, we have previously demonstrated that food intake at lunchtime in normal subjects has an inhibitory effect on the GH response to GHRH. The aim of the present study was to investigate the effect of food ingestion on GH secretion induced by HEX as compared to GHRH in six normal men (aged 23-29 years) and six normal women (aged 24-29 years). The body weights for all subjects were within 120% of their ideal body weight, according to their sex and age. Our data confirm that HEX is much more powerful than GHRH in inducing GH release in humans, both in the fasting state (GH-AUC: 3010 +/- 695 after HEX, vs. 1339 +/- 281 after GHRH, microg/L/120 min; p<0.06) and after a meal (GH-AUC: 1523 +/- 121, after HEX, vs. 309 +/- 61, after GHRH, microg/L/120 min; p<0.06). Moreover, our study shows that food intake partially blunts the fasting GH response to HEX (GH-AUC: 3010 +/- 695 after HEX, in fasting state, vs. 1523 +/- 121 after HEX, after meal, microg/L/120 min; p<0.06; mean inhibition of AUC 41.02 +/- 7.96%), whereas it nearly abolishes the GH response to GHRH in the same subjects (GH-AUC: 1339 +/- 281 after GHRH, in fasting state, vs. 309 +/- 61 after GHRH, after meal, microg/L/120 min; p<0.06; mean inhibition of AUC 70.31 +/- 6.22%). In conclusion, our study confirms that HEX acts differently from GHRH; the GH releasing effect of HEX could be only partially influenced by the physiological metabolic or neuroendocrine food-related modifications.

Effects of galanin on growth hormone and prolactin secretion in anorexia nervosa

Galanin (GAL) elicits growth hormone (GH) release in normal subjects through interaction with hypothalamic somatostatin. GAL also stimulates GH-releasing hormone (GHRH) secretion in vitro. In rats, GAL is able to stimulate prolactin (PRL) release, but this effect is not clear in humans. We have thus investigated GAL effects on GH and PRL release in patients with anorexia nervosa (AN), known to have altered regulation of the GH-insulin-like growth factor axis and PRL dynamics, and compared the effects of GHRH and GAL on GH and PRL secretion in AN and normal healthy subjects. Eight women with AN (15 to 27 years; body mass index [BMI], 17 to 19.5 kg/m2) were treated with (1) GHRH 50 microg intravenous (IV) injection, (2) porcine GAL 500 microg infusion from -10 to +30 minutes, and (3) 135-minutes saline infusion as a control, respectively. Both peptides induced a significant increase in plasma GH in AN patients (peak level, 27.41 +/- 5.50 microg/L after GAL and 18.97 +/- 2.67 microg/L after GHRH). When data for AN patients and the control group were compared, GH peak levels after GAL were significantly higher in AN patients (27.41 +/- 5.50 v 13.64 +/- 2.32 microg/L), while GH peak levels after GHRH were not different between the 2 groups (18.97 +/- 2.67 v 15.98 +/- 3.88 microg/L). PRL levels significantly increased after both GHRH (peak, 11.70 +/- 2.80 microg/L) and GAL (peak, 18.02 +/- 5.10 microg/L) treatment in AN patients, but not in normal subjects. We conclude that GAL stimulates exaggerated GH release in AN patients as compared with normal controls, suggesting a dual hypothalamic interaction via both an increase in endogenous GHRH and a decrease in somatostatin secretion. Finally, GAL may act as a PRL secretagogue in AN patients.

Hypothalamic derangement in traumatized patients: growth hormone (GH) and prolactin response to thyrotrophin-releasing hormone and GH-releasing hormone

OBJECTIVE

To study the impact of severe head injury on both basal pituitary hormone secretion and the response to exogenous synthetic hypothalamic releasing factors (TRH and GHRH) in order to evaluate sequential changes in the central control of hypophyseal secretion in the days following head injury.

DESIGN

Prospective clinical study

PATIENTS

21 comatose male patients with head injuries, each intubated and ventilated, intensively monitored and having no previous endocrine problems.

MEASUREMENTS

AND RESULTS The GH and PRL responses to TRH (200 microg iv), and the GH and PRL responses to GHRH (50 microg iv) were evaluated, respectively, on the days 1 and 16 and on days 2, 7and 15 after admission. Daily blood samples were also collected for GH, PRL, TSH, T3 and T4 evaluation. In the basal samples taken on days 2, 7 and 15, IGF-I and cortisol were also determined. Nitrogen balance was assessed daily. On the day 1, TRH increased GH levels from 9.8 +/- 2.2 to 22.4 +/- 6.5 mU/l but failed to induce GH release on day 16. The PRL response to TRH was normal. The GH peak response to GHRH was normal on the day 2 (35.7 +/- 13.9 mU/l), but was increased on days 7 and 15 (68.3 +/- 10.7 mU/l on day 7; 73.8 +/- 9.2 mU/l on day 15, P < 0.01 vs. day 2). We found a significant PRL response to GHRH during the whole period of observation. In the daily evaluation, nitrogen balance was negative in all patients from the day 1 to 5. On average, all patients reached a positive nitrogen balance on the day 8. Compared to the day 2, a statistical increase in IGF-I concentration was observed on days 7 and 15.

CONCLUSIONS

The evaluation of pituitary dynamics in the acute phase of a severe injury demonstrates an alteration of GH and PRL secretion, which correlate with the aminergic and/or peptidergic derangements. Taken together, our data suggest augmented tone of both GHRH and somatostatin in the very acute phase, while an imbalance of releasing factors is hypothesized in the following days. The metabolic consequences of this neuroendocrine pattern could be advantageous in the rapid recovery from the cascade of events produced by the trauma, as documented by the increase in IGF-1 levels and the positive nitrogen balance.

Evaluation of pre- and postprandial growth hormone (GH)-releasing hormone-induced GH response in subjects with persistent body weight normalisation after biliopancreatic diversion

BACKGROUND

Obesity is characterised by growth hormone (GH) abnormalities, including a blunted response to stimulation and a 'paradoxical' increase after meals. The blunted GH release is reversed by a surgical intestinal bypass procedure. However, this does not mean that normal GH dynamics have been restored. The present study assessed whether post-surgical weight reduction in obese patients normalised the modulation of GH release produced by metabolic fuels.

SUBJECTS

Ten obese female subjects, aged 23-54 y, were studied before and after biliopancreatic diversion (BPD). All patients, after surgery, had experienced a significant reduction in body weight (mean body mass index (BMI) 25.78 +/- 1.01 kg/m2 vs 44.68 +/- 1.73 kg/m2). Two groups were also studied as controls: Ten normal body weight female subjects and ten patients suffering from anorexia nervosa (AN, mean BMI 17.46 +/- 1.12 kg/m2).

MEASUREMENTS

We have studied the GH response to a GH releasing hormone (GHRH) bolus (1 microg/kg i.v., at 13.00 h) before and after a standard meal.

RESULTS

In post-BPD subjects, the GH response to GHRH in the fasting state, was clearly augmented in comparison with the pre-BPD values (peak values 18.06 +/- 4.56 vs 3.24 +/- 0.68 microg/L). In post-BPD subjects the postprandial GH response was further augmented in comparison with the fasting test (peak 30.12 +/- 4.99 microg/L, P < 0.05). This pattern was similar to that observed in anorexic patients.

CONCLUSION

The surgical procedure restores a normal GH response to GHRH in the fasting state, but the 'paradoxical' GH response after meals remains present, suggesting a persistent GH derangement in such patients, which is not related to body weight per se. The surgical procedure makes obese patients similar to anorexics, in the relationships between metabolic fuels and GH secretion. The persistence of the GH postprandial response to GHRH in post-BPD subjects suggests a role for metabolic fuels in the regulation of somatostatin (SRIF) secretion.

Physiological role of the opioid-cholinergic interaction in growth hormone neuroregulation: effect of sex and food intake

Studies performed in animals and humans have suggested a functional interaction between opioid and cholinergic systems in the control of growth hormone (GH) secretion. Moreover, the sex-dependent modulation of GH secretion in humans is well established. To investigate the role of sex and food intake in the regulation of the reciprocal influences of opioids and acetylcholine in the modulation of GH secretion, we studied the GH response to pyridostigmine (PYR) alone and during a naloxone (NAL) infusion in a group of normal men and women before a meal (at 1:00 PM) and postprandially. In women, the response of GH to PYR alone before the meal was significantly lower than in the men (area under the curve [AUC], mean +/- SEM, 320.18 +/- 87.16 v 1,031.06 +/- 333.21 micrograms/L/90 min, P < .01). Before the meal, NAL completely abolished the response of GH to PYR in men (AUC, 1,031.06 +/- 333.21 v 16.50 +/- 7.50 micrograms/L/90 min, P < .01), whereas infusion of NAL did not significantly modify the GH response to PYR in women. Consumption of the meal significantly decreased PYR-induced GH release in both women (AUC, 21.75 +/- 12.75 v 320.18 +/- 87.16 micrograms/L/90 min, P < .05) and men (AUC, 45.75 +/- 18.75 v 1,031.06 +/- 333.21 micrograms/L/90 min, P < .01). Conversely, food intake did not change the effects of NAL infusion on the GH response to PYR either in women or in men. We conclude that the sex-dependent opioid modulation of PYR-induced GH secretion is observed before a meal but not in the postprandial state. Food intake may be hypothesized to influence the cholinergic regulation of GH secretion and the sex-dependent opioid modulation of central cholinergic tone.