Somatostatin Analogs and Glucose Metabolism in Acromegaly: A Meta-analysis of Prospective Interventional Studies

Long-term pasireotide therapy in acromegaly: extensive real-life experience of a referral center

PURPOSE

Pasireotide is a novel therapeutic option for patients with acromegaly resistant to first-generation somatostatin receptor ligands. To date, real-life data are still scant, therefore, the aim of the current study is to evaluate the impact of long-term pasireotide therapy on disease control, pituitary tumor size, gluco-insulinemic and lipid profile in a real-life setting.

METHODS

Retrospective study of data prospectively collected, evaluating hormonal, tumoral, and metabolic data of 28 patients with acromegaly administered with pasireotide in a pituitary tertiary referral center.

RESULTS

Within the first 12 months of treatment, 70.4% of patients achieved normal IGF-I levels, which was maintained at 36-month evaluation in these responders patients. Patients who started with pasireotide 60 mg monthly exhibited significantly lower IGF-I levels after 36 months (p = 0.05) as compared to patients administered first with pasireotide 20 or 40 mg monthly. The maximal tumoral diameter was significantly decreased after 12 months of pasireotide (p < 0.001) and a further reduction was registered throughout the following months, with 41.2% of patients achieving a significant reduction (> 25% of baseline measurement) after 36 months of treatment. Fasting glucose significantly increased during the first 6 months (p < 0.001) with a gradual rise in diabetes prevalence during the following months, resulting diabetes prevalence after 36 months of pasireotide significantly increased compared to baseline (p = 0.003), although with glycated hemoglobin levels within the normal range. Diabetes was managed using oral glucose-lowering drugs or glucagon-like peptide 1 agonists, with no patient requiring insulin therapy. Pasireotide improved lipid profile, mainly during the first 12 months of treatment, by increasing HDL and decreasing triglycerides levels.

CONCLUSION

Pasireotide is effective and safe in the long-term. Hyperglycemia is a common event and is manageable even without insulin treatment.

Long-term depot specific changes in adipose tissue after treatment of acromegaly

CONTEXT

Patients with active acromegaly present a decreased adipose tissue (AT) mass, and short-term studies show that treatment leads to AT depot-specific gain. However, it remains unclear if the increase is persistent in the long-term perspective and/or is sex-dependent.

DESIGN

To characterize the depot-specific changes of AT after treatment of acromegaly and identify contributing factors.

METHODS

Adipose tissue, including visceral (VAT), subcutaneous (SAT), and total (TAT), and android to gynoid ratio (A/G ratio) were measured by dual energy X-ray absorptiometry at diagnosis (n = 62), and after treatment at short-term (median (IQR) 1.9 (1.5-2.3)) and long-term 5.5 (3.9-9.5) years, and correlated to clinical and biochemical measurements. Growth hormone (GH), insulin-like growth factor 1 (IGF-1), glucose and HbA1c levels, gonadal status, and the presence of diabetes mellitus were recorded. Remission status was assessed at the long-term visit (IGF-1/ULN ≤ 1.3). Differences in the temporal course of AT from baseline to short- and long-term follow-up according to sex, diabetes, gonadal, and remission status were evaluated by mixed model analysis, adjusted for age.

RESULTS

Despite a stable body mass index, VAT and A/G ratio increased at both time points, whereas SAT mainly increased at short-term, plateauing afterwards (P < .05 for all). Visceral adipose tissue and A/G ratio were higher in men (P = .035 and P < .001), and the A/G ratio increased more than in women (P = .003). Glucose and HbA1c decreased short-term (P < .05) and remained stable at long-term. The increase in AT depots correlated with the decrease of disease activity at long-term. Remission status had no effect on changes in AT mass during follow-up.

CONCLUSION

Treatment of acromegaly leads to an increase in AT mass in a depot- and sex-specific manner both at short-term and long-term follow-up. Glucose metabolism improves rapidly after disease control and persists.

Control of acromegaly in more than 90% of patients after 10 years of pegvisomant therapy: an European referral centre real-life experience

PURPOSE

Pegvisomant (PEG) efficaciously controls IGF-I excess in acromegaly and possesses a positive impact on glucose metabolism. Data on very prolonged PEG treatment are still limited, therefore, we investigated the effects of 10-years PEG on disease control, maximal tumour diameter (MTD), and metabolic profile in consecutive patients resistant to somatostatin analogues (SRLs) followed in an European referral centre for acromegaly.

METHODS

Since the 2000s, we collected data on anthropometric, hormonal and metabolic parameters, and MTD of patients receiving PEG. In the current study, we included 45 patients (19 men, 26 women, 46.8 ± 11 years) treated for at least 5 years with PEG mono or combined therapy, analyzing data before, after 5- and 10-years PEG.

RESULTS

After10 years, 91% of patients showed full disease control and in 37% a significant decrease in MTD was found. Diabetes prevalence was slightly increased, whereas HbA1c remained stable over the decade. Transaminases remained stable and no case of cutaneous lipohypertrophy was recorded. A different metabolic impact between mono- or combined therapy was found. Patients in monotherapy showed significantly lower fasting glucose (p = 0.01), fasting insulin (p = 0.008), HbA1c (p = 0.007), HOMA-IR (p = 0.001), and significantly higher ISI₀ (p = 0.002), whereas patients under combined therapy showed significantly lower total (p = 0.03), and LDL cholesterol (p = 0.007). Acromegaly duration before PEG was inversely related to ΔFG (r = - 0.46, p = 0.03) and ΔFI (r = - 0.54, p = 0.05).

CONCLUSIONS

PEG is effective and safe in long term. In patients resistant to SRLs, early beginning of PEG allows a wider gluco-insulinemic improvement.

Type 1 and other types of diabetes mellitus in the perioperative period. What the anaesthetist should know

Diabetes mellitus is often treated as a uniform disease in the perioperative period. Type 2 diabetes is most commonly encountered, and only a minority of surgical patients have been diagnosed with another type of diabetes. Patients with a specific type of diabetes can be particularly prone to perioperative glycaemic dysregulation. In addition, certain type-related features and pitfalls should be taken into account in the operating theatre. In this narrative review, we discuss characteristics of types of diabetes other than type 2 diabetes relevant to the anaesthetist, based on available literature and data from our clinic.

Prescription patterns of somatostatin analogs in patients with acromegaly and neuroendocrine tumors

PURPOSE

Acromegaly and neuroendocrine tumors are rare diseases that, under certain conditions, can be treated with somatostatin analogs. The aim was to determine the prescription patterns of somatostatin analogs in a group of patients with acromegaly and neuroendocrine tumors affiliated with the Colombian Health System.

METHODS

A retrospective study. A cohort of patients from a drug dispensing database that collected all prescriptions of long-acting somatostatin analogs (octreotide, lanreotide, pasireotide). Sociodemographic variables, clinical variables (diagnosis and comorbidities) and pharmacological therapy variables (dose, changes, persistence of use, comedications) were considered.

RESULTS

A total of 213 patients were identified, including 139 (65.3%) with acromegaly and 74 (34.7%) with neuroendocrine tumors. There was a predominance of women (58.7%) and a mean age of 59.7 ± 14.5 years. The most commonly used medications were lanreotide autogel (n = 107; 50.2%), octreotide LAR (n = 102; 47.9%) and pasireotide LAR (n = 4; 1.9%). During follow-up, 11.3% of patients experienced modifications of therapy, with a mean duration from the beginning of treatment to the change in medication of 25 ± 15.9 months. A total of 48.9% of the patients with acromegaly and 87.1% of individuals with neuroendocrine tumors received maximum approved doses of the drug.

CONCLUSION

Patients with acromegaly and neuroendocrine tumors in Colombia are mainly women and are most frequently treated with lanreotide autogel for acromegaly and with octreotide LAR for neuroendocrine tumors. In addition, a high proportion are managed with maximum doses of long-acting somatostatin analogs.

Acromegaly: pathogenesis, diagnosis, and management

Growth hormone-secreting pituitary adenomas that cause acromegaly arise as monoclonal expansions of differentiated somatotroph cells and are usually sporadic. They are almost invariably benign, yet they can be locally invasive and show progressive growth despite treatment. Persistent excess of both growth hormone and its target hormone insulin-like growth factor 1 (IGF-1) results in a wide array of cardiovascular, respiratory, metabolic, musculoskeletal, neurological, and neoplastic comorbidities that might not be reversible with disease control. Normalisation of IGF-1 and growth hormone are the primary therapeutic aims; additional treatment goals include tumour shrinkage, relieving symptoms, managing complications, reducing excess morbidity, and improving quality of life. A multimodal approach with surgery, medical therapy, and (more rarely) radiation therapy is required to achieve these goals. In this Review, we examine the epidemiology, pathogenesis, diagnosis, complications, and treatment of acromegaly, with an emphasis on the importance of tailoring management strategies to each patient to optimise outcomes.

Effect of Diabetes on Morbidity and Mortality in Patients With Acromegaly

CONTEXT

Diabetes is a major risk factor for cardiovascular disease and death but its effect on outcomes in acromegaly is unknown.

OBJECTIVE

This work aimed to study whether diabetes affects morbidity and mortality in patients with acromegaly.

METHODS

A nationwide (Sweden), observational, matched-cohort study was conducted. Patients diagnosed with acromegaly between 1987 and 2020 were identified in the Swedish National Patient Registry and those with concomitant type 2 diabetes in the National Diabetes Registry and Drug Registry. The risk of overall mortality, and cardiovascular mortality and morbidity were estimated using Cox regression.

RESULTS

The study included 254 patients with acromegaly and concomitant type 2 diabetes (ACRO-DM group) and 532 without diabetes (ACRO group). Mean (SD) age at baseline was 62.6 (11.4) and 60.0 (12.1) years (P = .004) and the mean (SD) duration of acromegaly was 6.8 (8.1) and 6.0 (6.2) years (P = .098) in the ACRO-DM and ACRO groups, respectively. Overall mean follow-up was 9.2 years. The unadjusted overall mortality rate per 1000 person-years was 35.1 (95% CI, 27.2-44.7) and 20.1 (95% CI, 16.5-24.3) in the respective groups. The hazard ratio (HR) for overall mortality adjusted for multiple confounders was 1.58 (95% CI, 1.12-2.23) in the ACRO-DM group compared with the ACRO group. Cardiovascular mortality (HR 2.11; 95% CI, 1.09-4.10) and morbidity (HR 1.49; 95% CI, 1.21-1.82) were also increased in the ACRO-DM group.

CONCLUSION

The presence of diabetes in patients with acromegaly was associated with increased overall mortality as well as increased cardiovascular mortality and morbidity.

The effects of somatostatin analogues on glycaemia in the treatment of neuroendocrine tumours

Long-acting somatostatin analogues (SSAs) are the most commonly used drugs in the management of neuroendocrine tumours (NETs) because of their ability to control symptoms and prolong survival. SSA use is associated with changes in glucose metabolism. However, the impacts on glycaemic control and body mass index (BMI) caused by SSAs in NETs are largely unknown. In the present study, we evaluated the effects of SSA treatment on BMI and glycated haemoglobin (HbA1c) in our cohort of patients with NETs. We also assessed changes in glycaemic control and BMI before and after SSA treatment. In addition, we assessed the incidence of new diabetes or whether there was worsening of glycaemic control for patients with pre-existing diabetes. The study comprised a retrospective study of 279 patients with NETs who were treated with SSAs between January 2014 and January 2019. Glycaemic control was assessed by measuring changes in Hba1c. A number needed to harm analysis was used to look at new cases of diabetes within the study population. Treatment with SSAs was associated with a mean increase in HbA1c of 3.35 ± 6.30 mmol mol^-1 despite a mean decrease in BMI of -1.04 ± 2.79 kg m^-2 . There were 19 new cases of type 2 diabetes mellitus (T2DM) in the population of 209 with a number needed to harm of 12.5. Of the 34 patients with pre-existing T2DM, five had worsening of their mean HbA1c. Treatment with SSAs for NETs is associated with an increase in HbA1c, despite a reduction in BMI and, importantly, a risk of developing T2DM with a number needed to harm of 12.5. This project was registered with the National Health Service Clinical Audit and Registries. It has a CARMS number - 17666.

Personalized Medical Treatment in Patients with Acromegaly: A Review

Acromegaly is associated with significant morbidity and mortality if not appropriately treated. In addition to insulin-like growth factor 1 (IGF-1) and growth hormone (GH) normalization, and tumor shrinkage, treatment goals include symptom relief, managing complications and improving quality of life. Surgical resection is a first-line treatment in most patients, with few being pretreated pre-operatively with medications. Somatostatin receptor ligands (SRLs), injectable and more recently oral capsules, have been the cornerstone of first-line medical therapy for persistent disease. However, several factors, including sparsely granulated adenomas, absent/low somatostatin receptor (SSTR2) status, imaging T2-hyperintensity, young age and aryl hydrocarbon receptor interacting protein mutations could predict first-generation SRL resistance. Patients with these characteristics may be better candidates for the GH receptor antagonist, pegvisomant, or in cases of large tumors the second-generation SRL, pasireotide. Combination therapy should be further pursued in patients who remain biochemically uncontrolled or have high remnant tumor after monotherapy. An efficacious and cost-effective pegvisomant dose-sparing effect of SRLs when used in combination has been demonstrated. With such a wide array of medical treatment options, it is increasingly important to tailor treatment to patients' unique characteristics as well as preferences, with a goal of personalizing management to achieve high quality outcomes.

Methylome Analysis in Nonfunctioning and GH-Secreting Pituitary Adenomas

Pituitary adenomas (PAs), usually benign lesions, can sometimes present with "aggressive" features (rapid growth, local invasiveness, scarce response to conventional treatments). Despite the fact that a few genetic alterations have been associated to this clinical behavior, the role of epigenetic modifications, mainly methylation and miRNAs activity, is now opening new frontiers in this field. We evaluated the methylation profile of 21 PA (11 GH-omas, 10 nonfunctioning tumors-NFPAs) samples from TNS surgery and 5 normal pituitaries, collected at our neurosurgery between 2015 and 2017. DNA was extracted and sequenced, selecting 184,841 target regions. Moreover, methylation profiles were correlated with demographic, radiological, and clinicopathological features. NFPAs showed higher methylation levels vs. GH-omas, with 178 differentially methylated regions (DMRs) mainly consisting of noncoding and intronic sequences, and mostly localized in the open sea regions. We also found three hypermethylated genes (C7orf50, GNG7, and BAHCC1) involved in tumorigenesis processes and potentially influencing pituitary tumor pathophysiology. Among the clinicopathological features, only the maximum diameter resulted significantly higher in NFPAs. Our data provide further evidence of the complex epigenetic background of pituitary tumors. In line with the current literature, we confirmed a significant prevalence of hypermethylation in NFPAs vs. GH-omas, whose pathophysiological consequence is yet to be defined.

Effects of Long-Acting Somatostatin Analogues on Lipid Metabolism in Patients with Newly Diagnosed Acromegaly: A Retrospective Study of 120 Cases

The short-term effects of long-acting somatostatin analogues (SSAs) on lipid profiles in patients with acromegaly are not well studied. We retrospectively analyzed the effects of SSAs on lipid profiles and associated cardiovascular risk factors in a cohort of 120 newly diagnosed acromegaly patients. In this study, 69 females and 51 males were included. These patients were treated with either octreotide LAR (OCT) or lanreotide SR (LAN) for 3 months. After SSAs treatment, both GH and IGF-1 significantly decreased (p<0.001). Triglyceride (TG), total to high-density lipoprotein cholesterol (HDL-C) ratio, and lipoprotein (a) [Lp(a)] levels were significantly decreased, while HDL-C levels were increased (p<0.05). The reduction of mean serum GH (GH_m) was positively associated with the decrease of TG (r=0.305, p=0.001) and Lp(a) (r=0.257, p=0.005), as well as the increase of HDL-C (r=-0.355, p<0.001). The changes of lipid profiles were observed only in OCT group, but not in LAN group. In addition, systolic blood pressure (SBP) had significantly declined after SSAs treatment, with an average reduction of 4.4 mmHg (126.7±1.28 vs. 122.3±1.44 mmHg, p=0.003), while no change was observed regarding diastolic blood pressure (DBP) (p>0.05). Fasting insulin, fasting C-peptide, and HOMA-IR were significantly decreased after SSAs treatment. In conclusion, our current study revealed that short-term SSAs treatment improves lipid profiles and other cardiovascular risk factors in patients with acromegaly.

Reversible insulin resistance in muscle and fat unrelated to the metabolic syndrome in patients with acromegaly

BACKGROUND

Patients with active acromegaly exhibit insulin resistance despite a lean phenotype whereas controlled disease improves insulin sensitivity and increases fat mass. The mechanisms underlying this paradox remain elusive, but growth hormone (GH)-induced lipolysis plays a central role. The aim of the study was to investigative the molecular mechanisms of insulin resistance dissociated from obesity in patients with acromegaly.

METHODS

In a prospective study, twenty-one patients with newly diagnosed acromegaly were studied at diagnosis and after disease control obtained by either surgery alone (n=10) or somatostatin analogue (SA) treatment (n=11) with assessment of body composition (DXA scan), whole body and tissue-specific insulin sensitivity and GH and insulin signalling in adipose tissue and skeletal muscle.

FINDINGS

Disease control of acromegaly significantly reduced lean body mass (p<0.001) and increased fat mass (p<0.001). At diagnosis, GH signalling (pSTAT5) was constitutively activated in fat and enhanced expression of GH-regulated genes (CISH and IGF-I) were detected in muscle and fat. Insulin sensitivity in skeletal muscle, liver and adipose tissue increased after disease control regardless of treatment modality. This was associated with enhanced insulin signalling in both muscle and fat including downregulation of phosphatase and tensin homolog (PTEN) together with reduced signalling of GH and lipolytic activators in fat.

INTERPRETATION

In conclusion, the study support that uncontrolled lipolysis is a major feature of insulin resistance in active acromegaly, and is characterized by upregulation of PTEN and suppression of insulin signalling in both muscle and fat.

FUNDING

This work was supported by a grant from the Independent Research Fund, Denmark (7016-00303A) and from the Alfred Benzon Foundation, Denmark.

Lanreotide and diazoxide have comparable effects on glucose levels in an elderly Japanese insulinoma patient: a case report

An insulinoma is a pancreatic neuroendocrine tumor that causes hypoglycemia. In the elderly, as surgery is not always possible, drugs are an important alternative. However, the effects of lanreotide on insulinomas have not yet been elucidated. We report the case of an 85-year-old Japanese woman who was admitted for loss of consciousness and hypoglycemia, which was resolved after intravenous glucose infusion. Insulin secretion was not inhibited during hypoglycemia. Enhanced computed tomography and OctreoScan scintigraphy revealed a pancreatic tumor (diameter, 13 mm) with radiotracer accumulation. Thus, clinical insulinoma was confirmed. However, the patient refused further examination and surgery. Diazoxide (150 mg/day) therapy resolved hypoglycemia but caused fluid retention. Consequently, we switched to lanreotide (120 mg/6 weeks). Continuous glucose monitoring revealed that both drugs had comparable effects on interstitial glucose normalization. Furthermore, 447 days after the initiation of lanreotide treatment, the patient had no hypoglycemic symptoms. Therefore, lanreotide may be a useful alternative treatment option for inoperable insulinomas in elderly individuals.

Acromegaly: achieving timely diagnosis and improving outcomes by personalized care

PURPOSE OF REVIEW

Discuss recent literature regarding clinical manifestations and comorbidities in acromegaly, with focus on early diagnosis and customized care.

RECENT FINDINGS

The mean interval between onset of clinical manifestations and diagnosis is currently 3-5 years. Women, especially younger than 50 years of age, experience longer delays, have lower insulin-like growth factor 1 (IGF-1) levels and larger tumors than men. Development of comorbidities usually precedes the diagnosis and is influenced by age, sex, and biochemical disease activity. Comorbidities other than irreversible osteoarticular structural changes usually improve after acromegaly treatment. In patients with diabetes, the course of hyperglycemia not only depends on biochemical control but also on specific acromegaly therapies. Quality of life is influenced by sex, as well as by acromegaly symptoms, biochemical activity, and treatment. Quality of life remains lower than general population despite biochemical remission.

SUMMARY

Early diagnosis can be achieved by suspecting acromegaly based on suggestive clinical scenarios rather than obvious changes in appearance. Personalized care entails a proactive multidisciplinary approach to identify and treat comorbidities while carefully monitoring the effects of acromegaly treatment.

In patients with controlled acromegaly, indices of glucose homeostasis correlate with IGF-1 levels rather than with type of treatment

OBJECTIVE

Acromegaly is accompanied by abnormalities in glucose and lipid metabolism which improve upon treatment. Few studies have investigated whether these improvements differ between treatment modalities. This study aimed to compare glucose homeostasis, lipid profiles and postprandial gut hormone response in patients with controlled acromegaly according to actual treatment.

DESIGN

Cross-sectional study at a tertiary care centre.

PATIENTS

Twenty-one patients with acromegaly under stable control (ie insulin growth factor 1 [IGF1] levels below sex- and age-specific thresholds and a random growth hormone level <1.0 µg/L) after surgery (n = 5), during treatment with long-acting somatostatin analogues (n = 10) or long-acting somatostatin analogues + pegvisomant (n = 6) were included.

MEASUREMENTS

Glucose, insulin, total cholesterol and high-density lipoprotein-cholesterol were measured in fasting serum samples. Glucose, insulin, triglycerides, glucose-dependent insulinotropic polypeptide and glucagon-like peptide 1 were measured during a mixed meal test. Insulin sensitivity was evaluated by a hyperinsulinaemic-euglycaemic clamp.

RESULTS

There were no significant differences in glucose tolerance, insulin sensitivity or postprandial gut hormone responses between the three groups. Positive correlations between IGF1 levels and HbA1c, fasting glucose and insulin levels and postprandial area under the curve (AUC) of glucose and insulin and also an inverse association between IGF1 and glucose disposal rate were found in the whole cohort (all p < .05, lowest p = .001 for postprandial AUC glucose with r_s  = 0.660).

CONCLUSION

In this cross-sectional study in patients with controlled acromegaly, there were no differences in glucose homeostasis or postprandial substrate metabolism according to treatment modality. However, a lower IGF1 level seems associated with a better metabolic profile.

HOMA-IR in acromegaly: a systematic review and meta-analysis

PURPOSE

This review is aimed at examining whether the Homeostatic Model Assessment of Insulin Resistance (HOMA-IR) is higher in Caucasian, adult, treatment-naïve patients with acromegaly (ACRO) than in the reference population independently of diabetes presence and to evaluate the impact of treatment [surgery and somatostatin analogues (SSAs)] on its assessment.

METHODS

We systematically reviewed in PubMed and Web of Science from July 1985 to December 2019, registered with the code number CRD42020148737. The inclusion criteria comprised studies conducted in Caucasian adult treatment-naïve patients with active ACRO in whom HOMA-IR or basal insulin and glucose were reported. Three reviewers screened eligible publications, extracted the outcomes, and assessed the risk of biases.

RESULTS

Of 118 originally selected studies, 15 met the inclusion criteria. HOMA-IR was higher in ACRO than the reference population, with mean difference and (95% confidence intervals) of 2.04 (0.65-3.44), even in ACRO patients without diabetes, 1.89 (1.06-2.73). HOMA-IR significantly decreased after treatment with either surgery or SSAs - 2.53 (- 3.24- - 1.81) and - 2.30 (- 3.05- - 1.56); respectively. However, the reduction of HOMA-IR due to SSAs did not improve basal glucose.

CONCLUSION

HOMA-IR in treatment-naïve ACRO patients is higher than in the reference population, even in patients without diabetes. This finding, confirms that insulin resistance is an early event in ACRO. Our results also suggest that HOMA-IR is not an adequate tool for assessing insulin resistance in those patients treated with SSAs.

Patterns of Abnormal Glucose Metabolism in Acromegaly and Impact of Treatment Modalities on Glucose Metabolism

Background: Chronic exposure to high levels of growth hormone (GH) and insulin-like growth factor 1 (IGF-1) leads to metabolic complications, most importantly dysglycemia in the form of diabetes mellitus and pre-diabetes. Dysglycemia if diagnosed early in the course of the disease can decrease complications. Treatment modalities in the form of surgery and medical therapy have varied impacts on glucose metabolism.

Objective: To determine the frequency of diabetes mellitus, impaired glucose tolerance, and impaired fasting glucose in Pakistani patients with acromegaly and to establish the impact of the intervention (surgery/medical) on glucose metabolism.

Methods: This study was a retrospective review of patient records. Eighty-nine patients fulfilling the Endocrine Society criteria for acromegaly diagnosis were included. A data of baseline, GH, IGF-1 level, hemoglobin A1C (HbA1C), fasting blood glucose (FBG), and random blood glucose (RBS) levels were reviewed before and after the intervention (surgery/medical therapy). Normal glucose tolerance (NGT), impaired fasting glucose (IFG), impaired glucose tolerance (IGT), and diabetes mellitus (DM) were defined based on the American Diabetes Association (ADA) criteria. Patients were grouped into normoglycemic (NGT) and dysglycemic (IFG, IGT, and DM) based on FBG, RBS, and HbA1C.

Results: Major risk factors for dysglycemia included age (15-45 years), male sex (33.70%), obesity (45.7%), and macroadenoma (77.52%). Both mean GH levels (58.29 vs. 54.36 ng/dl) and IGF-1 levels (862.98 vs. 824.32 ng/dl) were higher among the normoglycemic than dysglycemia. Pre-surgery NGT, IFG, IGT, IFG, and IGT/DM combined were found in 48.31%, 5.61%, 1.1%, 5.61%, and 39.32% of the subjects respectively. Post-surgery, HbA1C improved in 79.5%, deteriorated in 6.8%, and remained the same in 13.6%. Similarly, it improved in 67% post-medical therapy. Both FBG and RBS improved post-surgery and medical therapy. Further, the number of anti-diabetic drugs used also decreased post-surgery.

Conclusion: Dysglycemia is more common among patients with acromegaly as compared to the general population and tends to be poorly controlled in untreated acromegaly. Glycemic control improves significantly after surgery and medical therapy.

The Interaction of Insulin and Pituitary Hormone Syndromes

Pituitary hormone axes modulate glucose metabolism and exert direct or indirect effects on insulin secretion and function. Cortisol and growth hormone are potent insulin-antagonistic hormones. Therefore impaired glucose tolerance, elevated fasting glucose concentrations and diabetes mellitus are frequent in Cushing's disease and acromegaly. Also prolactinomas, growth hormone (GH) deficiency, hypogonadism and hypothyroidism might be associated with impaired glucose homeostasis but usually to a lesser extent. Therefore glucose metabolism needs to be closely monitored and treated in patients with pituitary adenomas. Correction of the pituitary dysfunction is frequently followed by improvement of glucose homeostasis.

Combined therapy of somatostatin analogues with pegvisomant for the treatment of acromegaly: a meta-analysis of prospective studies

BACKGROUND

Acromegaly is a rare, chronic and severe disease. Drug therapy including somatostatin analogues (SAs), dopamine receptor agonists and growth hormone receptor antagonists (pegvisomant, PEG) are commonly used to treat patients who do not respond to surgery. The use of combination therapy with PEG and SAs has become more common over the last decade. We performed this study to accurately evaluate the effect of combination therapy of SAs with PEG on acromegalic patients.

METHODS

PubMed, EMBASE, The Cochrane Library, ClinicalTrials.gov, Scopus, Web of Science, Chinese Biomedical Literature Database and Trip database were searched for relevant studies. Prospective clinical trials treating acromegaly with the co-administration of SAs and PEG were included. We performed a meta-analysis by using Stata 12.1. Sensitivity analysis was conducted to explore heterogeneity.

RESULTS

Nine studies were included in this meta-analysis. The overall rate of serum insulin-like growth factor 1 (IGF-1) normalization was 66% (95% CI: 52-78%; I² = 62.59%). The combination therapy did not significantly change patients' fasting plasma glucose (ES: 0.011 mmol*L^- 1; 95% CI: - 0.374 to 0.397 mmol*L^- 1; P = 0.954) or glycosylated haemoglobin (ES: - 0.074%; 95% CI: - 0.166 to 0.315%; P = 0.544) while decreasing the fasting plasma insulin (ES: - 21.487 pmol*L^-1; 95% CI: - 35.713 to - 7.260 pmol*L^-1; P = 0.003). Elevation of liver enzyme levels was found in 14% (95% CI: 8 to 21%) of the patients. There was no significant difference for serious adverse events and treatment discontinuation due to adverse event between SAs monotherapy group and combination therapy group.

CONCLUSIONS

Combined therapy of SAs and PEG effectively normalized IGF-1 levels in most of the patients whose IGF-1 level was greater than the upper limit of normal after high dose SAs monotherapy. The therapy also decreased significantly FPI levels with a neutral effect on glucose parameters in acromegaly patients. Moreover, elevated liver enzyme levels were observed in a small number of patients, which suggests a need for liver function monitoring.

TRIAL REGISTRATION

We have our protocol registered in PROSPERO. (Registration number: CRD42019115549 ).

Drug treatment strategies for secondary diabetes in patients with acromegaly

INTRODUCTION

Acromegaly is a rare disease due to oversecretion of growth hormone (GH). Even though the disease is often portrayed by its most apparent clinical features, given the abundance of GH receptors throughout the body, it truly is a systemic disease leading to numerous complications and comorbidities. A distinct medical issue in the context of acromegaly is diabetes: It can be a complication as a consequence of GH excess and its mediators, but it can also result from treatment of acromegaly.

AREAS COVERED

This review provides an overview of the effects of acromegaly pathophysiology on glucose homeostasis. Furthermore, it devotes an extensive section on the influence that acromegaly treatment has on glucose metabolism, including approved as well as currently investigated drugs. It also summarizes observations from the use of anti-diabetic medication in patients with acromegaly.

EXPERT OPINION

Glucose imbalance is an important aspect of acromegaly comorbidity and deserves more attention. Even though numerous studies have investigated glucose homeostasis in acromegaly, there is still a clear need for more basic, translational, and also clinical research to advance the understanding of the underlying mechanisms and how to best address them.

Titanium dioxide nanoparticles via oral exposure leads to adverse disturbance of gut microecology and locomotor activity in adult mice

Titanium dioxide nanoparticles (TiO₂NPs) have been widely used as food additives in daily life. However, the impact of oral intake of TiO₂NPs on the nervous system is largely unknown. In this study, 7-week-old mice were treated with either vehicle or TiO₂NPs suspension solution at 150 mg/kg by intragastric administration for 30 days. Our results demonstrated that oral exposure to TiO₂NPs resulted in aberrant excitement of enteric neurons, although unapparent pathological changes were observed in gut. We also found the richness and evenness of gut microbiota were remarkably decreased and the gut microbial community compositions were significantly changed in the TiO₂NP-treated group as compared with vehicle controls. Interestingly, oral exposure to TiO₂NPs was capable to induce the inhibitory effects on locomotor activity, but it did not lead to significant change on the spatial learning and memory ability. We further revealed the mechanism that TiO₂NPs could specifically cause locomotor dysfunction by elevating the excitement of enteric neuron, which might spread to brain via gut-brain communication by vagal pathway. However, inflammation response, enteric neurotransmitter 5-HT and major gut peptides might not be involved in this pathological process. Together, these findings provide valuable insights into the novel mechanism of TiO₂NP-induced neurotoxicity. Understanding the microbiota-gut-brain axis will provide the foundation for potential therapeutic or prevention approaches against TiO₂NP-induced gut and brain-related disorders.

Cardiometabolic Risk in Acromegaly: A Review With a Focus on Pasireotide

Acromegaly is a disease due to chronic GH excess and a consequent rise in IGF-1 levels. This rare endocrine condition is associated with metabolic alterations such as hyperglycaemia, dyslipidaemia, and systemic arterial hypertension, which, in addition to GH excess-related cardiovascular changes, play critical roles in increasing cardiovascular risk and mortality rates. Biochemical control of acromegaly, achieved by means of surgical, and/or medical treatment, positively impacts on cardiovascular risk factors and metabolic alterations, reducing overall patient mortality. However, treatment modalities of acromegaly and disease control differently impact on glucose homeostasis and lipid changes, and consequently on cardiometabolic risk. In this regard, pasireotide was shown to significantly influence glucose metabolism. This review summarizes the cardiometabolic consequences of acromegaly and its treatment, focusing on available data around the effects of medical therapy with pasireotide on factors that influence cardiometabolic risk.

Italian Association of Clinical Endocrinologists (AME) and Italian AACE Chapter Position Statement for Clinical Practice: Acromegaly - Part 2: Therapeutic Issues

Any newly diagnosed patient should be referred to a multidisciplinary team experienced in the treatment of pituitary adenomas. The therapeutic management of acromegaly always requires a personalized strategy. Normal age-matched IGF-I values are the treatment goal. Transsphenoidal surgery by an expert neurosurgeon is the primary treatment modality for most patients, especially if there are neurological complications. In patients with poor clinical conditions or who refuse surgery, primary medical treatment should be offered, firstly with somatostatin analogs (SSAs). In patients who do not reach hormonal targets with first-generation depot SSAs, a second pharmacological option with pasireotide LAR or pegvisomant (alone or combined with SSA) should be offered. Irradiation could be proposed to patients with surgical remnants who would like to be free from long-term medical therapies or those with persistent disease activity or tumor growth despite surgery or medical therapy. Since the therapeutic tools available enable therapeutic targets to be achieved in most cases, the challenge is to focus more on the quality of life.

The position of combined medical treatment in acromegaly

Advances in combination medical treatment have offer new perspectives for acromegaly patients with persistent disease activity despite receiving the available medical monotherapies. The outcomes of combination medical treatment may reflect both additive and synergistic effects. This review focuses on combination medical treatment and its current position in acromegaly, based on clinical studies evaluating the efficacy and safety of combined medical treatment(s) and our own experiences with combination therapy. Arch Endocrinol Metab. 2019;63(6):646-52.

The Interplay Between Pituitary Health and Diabetes Mellitus - The Need for 'Hypophyseo-Vigilance'

The anterior and posterior hypophyseal hormones alter glucose metabolism in health and disease. Secondary diabetes may occur due to hypersecretion of anterior pituitary hormones like adrenocorticotrophic hormone in Cushing's disease and growth hormone in acromegaly. Other hormones like prolactin, gonadotropins, oxytocin and vasopressin, though not overtly associated with causation of diabetes, have important physiological role in maintaining glucose homeostasis. Hypoglycaemia is not an unusual occurrence in hypopituitarism. Many of the medications that are used for treatment of hypophyseal diseases alter glucose metabolism. Agents like pasireotide should be used with caution in the setting of diabetes, whereas pegvisomant should be given preference. Diabetes mellitus itself, on the other hand, can alter the functioning of hypothalamic pituitary axis; this is documented in both type 1 and type 2 diabetes. This review focuses on the clinically relevant interplay of hypophyseal hormones and glucose homeostasis. The authors define 'hypophyseo-vigilance' as an approach which keeps the bidirectional, multifaceted interactions between the pituitary and glucose metabolism in mind while managing diabetes and pituitary disease.

Metabolic Fingerprint of Acromegaly and its Potential Usefulness in Clinical Practice

Insulin-like growth factor-1 (IGF-1) and growth hormone (GH) levels are the main targets for monitoring acromegaly activity, but they are not in close relationship with the clinical course of the disease and the associated comorbidities. The present study was aimed at identifying metabolites that could be used as biomarkers for a better disease phenotyping. For this purpose, metabolic fingerprint using an untargeted metabolomic approach was examined in serum from 30 patients with acromegaly and 30 age-matched controls. Patients with acromegaly presented fewer branched-chain amino acids (BCAAs) compared to the control group (valine: 4.75 ± 0.87 vs. 5.20 ± 1.06 arbitrary units (AUs), p < 0.05; isoleucine: 2.54 ± 0.41 vs. 2.80 ± 0.51 AUs; p < 0.05). BCAAs were also lower in patients with active disease compared to patients with normal levels of IGF-1 with or without medical treatment. GH, but not IGF-1, serum levels were inversely correlated with both valine and isoleucine. These findings indicate that low levels of BCAAs represent the main metabolic fingerprint of acromegaly and that GH, rather than IGF-1, might be the primary mediator. In addition, our results suggest that the assessment of BCAAs could help to identify active disease and to monitor the response to therapeutic strategies.

Current perspectives on the impact of clinical disease and biochemical control on comorbidities and quality of life in acromegaly

Acromegaly is a rare chronic, systemic disorder caused by excessive growth hormone (GH) secretion from a somatotroph pituitary adenoma. GH hypersecretion leads to overproduction of insulin-like growth factor-1 (IGF-1), which contributes to the somatic overgrowth, physical disfigurement, onset of multiple systemic comorbidities, reduced quality of life (QoL) and premature mortality of uncontrolled patients. Somatostatin receptor ligands, dopamine agonists and a GH receptor antagonist are currently available for medical therapy of acromegaly. The main aim of treatment is biochemical normalisation, defined as age-normalised serum IGF-1 values and random GH levels <1.0 μg/L. However, there is an increasing evidence suggesting that achieving biochemical control does not always decrease the burden of disease-related comorbidities and/or improve patients' QoL. This lack of correlation between biochemical and clinical control can be due to both disease duration (late diagnosis) or to the peculiarity of a given comorbidity. Herein we conducted ad hoc literature searches in order to find the most recent and relevant reports on biochemical and clinical disease control during medical treatment of acromegaly. Particularly, we analyse and describe the relationship between biochemical, as well as clinical disease control in patients with acromegaly receiving medical therapy, with a focus on comorbidities and QoL. In conclusion, we found that current literature data seem to indicate that clinical disease control (besides biochemical control), encompassing clinical signs and symptoms, comorbidities and QoL, emerge as a primary focus of acromegaly patient management.

Pegvisomant Improves Glucose Metabolism in Acromegaly: A Meta-Analysis of Prospective Interventional Studies

INTRODUCTION

Pegvisomant (PEG) in monotherapy or combined with somatostatin analogs (SSAs) is used to control acromegaly, improving metabolism. However, the metabolic changes induced by PEG have not been systematically reviewed.

OBJECTIVE

To address the following questions: does PEG or the combination of PEG and SSAs affect fasting plasma glucose (FPG), glycosylated Hb (HbA1c), glucose load (2-hour oral glucose tolerance test), insulin levels [fasting plasma insulin (FPI)], homeostatic model assessment of insulin resistance (HOMA-I), homeostatic model assessment of β-cell function, lipid profile, or body mass index? Are the effects disease-related or drug-related?

DATA SOURCES

Indexed databases up to January 2019.

STUDY SELECTION

Prospective interventional trials reporting glycometabolic outcomes under PEG or PEG plus SSAs for a minimum of 6 months.

DATA EXTRACTION

Three reviewers screened eligible publications (7248), three others extracted the outcomes, and all assessed the risk of biases.

DATA SYNTHESIS

Thirteen studies were included in the PEG and 5 in the PEG plus SSAs analysis (overall 550 subjects). PEG significantly decreased FPG [effect size (ES) -0.80 mmol/L (95% CI, -1.06 to -0.55); P = 0.000], HbA1c [ES -0.43% (95% CI, -0.56 to -0.31); P = 0.000], FPI [ES -5.31 mU/L (95% CI, -10.23 to -0.39); P = 0.034], and HOMA-I [ES -0.61 (95% CI, -1.17 to -0.04); P = 0.034]. Effects on FPG and FPI were not correlated to IGF-1 changes. The addition of PEG to SSAs mitigated the effects of SSAs on metabolism, producing an overall neutral effect.

CONCLUSIONS

Independently of disease control, PEG in monotherapy or combined with SSAs seems to improve glucose metabolism, reducing FPG, HbA1c, FPI, and HOMA-I.

Sodium Glucose Co-transporter Inhibitors in Patients with Acromegaly and Diabetes

Acromegaly per se predisposes to diabetes. Somatostatin analogs (SSAs) have an overall neutral effect on glycemic control. However, a marked increase in hyperglycemia was observed recently since the introduction of pasireotide long-acting release (PAS-LAR). Sodium glucose cotransporter inhibitors (SGLT2is) have proven their efficacy, cardiovascular safety, and superiority in the management of type 2 diabetes mellitus (T2DM). However, this class is rarely recommended for patients with diabetes and acromegaly. A decreased circulating insulin level is considered unique for this class and might have a beneficial role in the growth hormone-insulin-like growth factor-I (GH-IGF-I) axis. Therefore, SGLT2is should be considered in the management of diabetes in patients with acromegaly. This article highlights the role of this novel class for the management of diabetes in patients with acromegaly.

The Endothelium in Acromegaly

Growth hormone (GH) and insulin like growth factor-1 (IGF-1) excess induce well-known deleterious effects on the cardiovascular system, especially after long-term exposition. Acromegaly, a condition of chronic GH and IGF-1 hypersecretion, is frequently associated to cardiovascular complications, although recent studies have shown a reduction in the prevalence of these comorbidities in well-controlled patients and a mortality risk similar to normal aging population. Many factors could contribute to the increased cardiovascular risk of acromegaly patients. Among these factors, the endothelium plays a key role in the pathogenesis of atherosclerotic plaques and could be considered an early marker of atherosclerosis and cardiovascular dysfunction. In this review we examined the relationship between GH/IGF-1 excess and the endothelium, from basic studies to clinical evidence. Many studies involving various arterial districts (microvascular arteries of retina, kidney and brain, and major vessels as carotid and aorta) showed that GH/IGF-1 excess promotes endothelial dysfunction via several different mechanisms. Increased endothelial proliferation, dysfunction of endothelial progenitor cells, increased oxidative stress, and compromised oxidative defenses are the main factors that are associated with endothelial dysfunction. In the general population, these alterations are associated with the development of atherosclerosis with an increased incidence of coronary artery disease and cerebrovascular complications. However, in acromegaly this is still a debated issue, despite the presence of many pro-atherogenic factors and comorbidities, such as hypertension, diabetes, sleep apnoea, and metabolic syndrome. Preclinical markers of atherosclerosis as arterial intima media thickness, pulse wave velocity and flow mediated dilation seem to be impaired in acromegaly and partly mediated by the endothelium dysfunction. In conclusion, the pathophysiology of endothelial dysfunction in the condition of GH and IGF-1 excess remains a crucial area of investigation to fully dissect the association of acromegaly with cardiovascular disease complications.

Insulin Resistance in Patients With Acromegaly

Acromegaly is characterized by chronic overproduction of growth hormone (GH) that leads to insulin resistance, glucose intolerance and, ultimately, diabetes. The GH-induced sustained stimulation of lipolysis plays a major role not only in the development of insulin resistance and prediabetes/diabetes, but also in the reduction of lipid accumulation, making acromegaly a unique case of severe insulin resistance in the presence of reduced body fat. In the present review, we elucidate the effects of GH hypersecretion on metabolic organs, describing the pathophysiology of impaired glucose tolerance in acromegaly, as well as the impact of acromegaly-specific therapies on glucose metabolism. In addition, we highlight the role of insulin resistance in the development of acromegaly-associated complications such as hypertension, cardiac disease, sleep apnea, polycystic ovaries, bone disease, and cancer. Taken together, insulin resistance is an important metabolic hallmark of acromegaly, which is strongly related to disease activity, the development of comorbidities, and might even impact the response to drugs used in the treatment of acromegaly.

Disposition Index in Active Acromegaly

Background: The relative contribution of reduced insulin sensitivity (S_i) or insulin secretion to impaired fasting glucose (IFG) or diabetes mellitus (DM) has not been clarified in active acromegaly. An intravenous glucose tolerance test (IVGTT) was never used for the calculation of S_i, acute insulin response (AIR_g), and disposition index (DI) in this population. Our aim was to assess S_i, AIR_g and DI using an IVGTT in acromegaly with normal (NGT) and abnormal glucose tolerance. Methods: We performed an IVGTT in 13 patients (8 NGT, 2 IFG, and 3 DM; 5 males, age 47.9 ± 11 years, body mass index 29.7 ± 4.1 kg/m²) with active acromegaly (insulin-like growth factor-1 4.1 ± 1.3 × upper limit of normal, basal GH 29.1 ± 25 ng/mL) and 3 healthy controls (2 males, age 39 ± 3 years, body mass index 23 ± 5 kg/m²). No patient had any growth hormone- or glucose-lowering medication. Results: NGT patients had significantly lower S_i than healthy controls but higher AIR_g. Hyperglycemic and normoglycemic patients had similar S_i. DM patients had severely diminished AIR_g (5-260 pmol × min/L) while IFG patients maintained their insulin secretion (3,862 and 912 pmol × min/L). Patients with abnormal glucose tolerance (IFG + DM) had a significantly lower DI (353 ± 350) than both NGT patients (3,685 ± 2,544) and healthy controls (5,837 ± 1,894; p < 0.01 for ANOVA). Conclusions: Disposition index suggests that although reduced insulin sensitivity is characteristic of active acromegaly it is the impaired insulin secretion that mainly drives glucose intolerance. The clinical utility of DI in predicting DM in acromegaly must be further investigated.

Diabetes Secondary to Acromegaly: Physiopathology, Clinical Features and Effects of Treatment

Acromegaly is a rare disease due to chronic GH excess and to the consequent increase in IGF-1 levels. Both GH and IGF-1 play a role in intermediate metabolism affecting glucose homeostasis. Indeed, chronic GH excess impairs insulin sensitivity, increases gluconeogenesis, reduces the glucose uptake in adipose tissue and muscle and alters pancreatic β cells function. As a consequence, glucose metabolism alterations are a very frequent complication in acromegaly patients, further contributing to the increased cardiovascular risk and mortality. Treatment modalities of acromegaly differently impact on glucose tolerance. Successful surgical treatment of acromegaly ameliorates glucose metabolism abnormalities. Drugs used to treat acromegaly patients may per se affect glucose homeostasis, therefore influencing patients' management. Indeed pegvisomant has been shown to positively impact on glucose metabolism, while somatostatin analogs, especially pasireotide, can cause hyperglycaemia. On the other hand, robust data on the effect of dopamine agonists on glycaemic profile are still lacking. This review summarizes the available data on diabetes mellitus in acromegaly patients, with a focus on the potential effects of the medical treatment of the disease on glucose homeostasis, providing an overview of the current state of the art.

Hepatic Steatosis Index in Acromegaly: Correlation with Insulin Resistance Regardless of the Disease Control

OBJECTIVE

In acromegaly, both lipotoxicity secondary to GH excess and insulin resistance have a significant impact on the liver. Ultrasonography has shown poor sensitivity in detecting hepatic steatosis and noninvasive methods have been proposed. We evaluated the hepatic steatosis index (HSI), a validated surrogate index of hepatic steatosis, and we correlated it with disease activity and insulin resistance.

DESIGN

Thirty-one patients with newly diagnosed acromegaly were studied at diagnosis and after 12 months of treatment with somatostatin receptor ligands.

METHODS

Glucose and insulin levels, surrogate estimates of insulin sensitivity, and hepatic steatosis through ultrasonography and HSI were evaluated.

RESULTS

At diagnosis, ultrasonography documented steatosis in 19 patients (61.2%) while 26 (83.8%) showed high HSI. After 12 months, both GH (p = 0.033) and IGF-1 (p < 0.001) significantly decreased and, overall, 58% of patients were classified as controlled. Ultrasonography documented steatosis in all the same initial 19 patients, while only 14 patients (45.1%) showed high HSI (p < 0.001). A significant reduction in HOMA-IR (p = 0.002) and HSI (p < 0.001) and increased ISI Matsuda (p < 0.001), was documented. The change of HSI from baseline to 12 months was found to be directly correlated with the change of ISI (Rho -0.611; p = 0.004) while no correlation was found with the change of GH or IGF-1 levels and other parameters.

CONCLUSIONS

In acromegaly, HSI is mainly related with insulin resistance and the reduction of GH and IGF-1 levels, and above all the improvement in insulin sensitivity leads to an improvement of this surrogate index of hepatic steatosis.