Insulin Resistance in Patients With Acromegaly

Cutaneous findings in patients with acromegaly and its relationship with concomitant endocrinopathies

OBJECTIVES

Skin changes in acromegaly are often the first sign of the disease. The aim of this study was to describe the cutaneous findings in patients with acromegaly. In addition, a secondary aim was to investigate the possible association of these findings with remission status and concomitant endocrinopathies.

DESIGN, PATIENTS, AND MEASUREMENTS

In this prospective multicenter study, 278 patients over the age of 18 years with acromegaly who were followed up in 14 different tertiary healthcare institutions were included. These patients, who were followed up by the Endocrinology Department, were then referred to a dermatologist for dermatological examination. The frequency of skin lesions was investigated by detailed dermatologic examination. Dermatological diagnosis is reached by clinical, dermatological and/or dermoscopic examination, and rarely skin punch biopsy examinations in suspicious cases. The possible association of the skin findings between remitted and nonremitted patients and with concomitant endocrinopathies were evaluated.

RESULTS

The most common skin findings in patients with acromegaly in our study were skin tags (52.5%), cherry angiomas (47.4%), seborrhoea (37%), varicose veins (33%), acneiform lesions (28.8%), hyperhidrosis (26.9%) and hypertrichosis (18.3%). Hypertrichosis was significantly more prevalent in patients nonremitted (p: .001), while xerosis cutis was significantly more prevalent in patients remitted (p: .001). The frequency of diabetes mellitus and hypothyroidism was significantly higher in patients with varicose veins and seborrhoeic keratosis than those without. Additionally, the coexistence of hypothyroidism, hyperthyroidism and galactorrhea was significantly higher in patients with Cherry angioma than in those without Cherry angioma (p-values: .024, .034 and .027, respectively). The frequency of hypogonadism in those with xerosis cutis was significantly higher than in those without (p: .035).

CONCLUSIONS

Cutaneous androgenization findings such as skin tag, seborrhoea, acne and acanthosis nigricans are common in patients with acromegaly. Clinicians should be aware that skin findings associated with insulin resistance may develop in these patients. It can be said that the remission state in acromegaly has no curative effect on cutaneous findings. Only patients in remission were less likely to have hypertrichosis. This may allow earlier review of the follow-up and treatment of acromegaly patients presenting with complaints of hypertrichosis. Additionally, it can be said that patients with skin findings such as cherry angioma may be predisposed to a second endocrinopathy, especially hypothyroidism. Including dermatology in a multidisciplinary perspective in acromegaly patient management would be beneficial to detect cutaneous findings earlier.

Acromegalic Cardiomyopathy: An Entity on its own? The Effects of GH and IGF-I Excess and Treatment on Cardiovascular Risk Factors

Acromegaly is a chronic disease resulting from constantly elevated concentrations of growth hormone (GH) and insulin-like growth factor I (IGF-I). If not adequately treated, GH and IGF-I excess is associated with various cardiovascular risk factors. These symptoms mainly include hypertension and impaired glucose metabolism, which can be observed in approximately one-third of patients. Other comorbidities are dyslipidemia and the presence of obstructive sleep apnea syndrome. However, even in the absence of conventional cardiovascular risk factors, myocardial hypertrophy can occur, which reflects the impact of GH and IGF-I excess itself on the myocardium and is defined as acromegalic cardiomyopathy. Whereas previous echocardiography-based studies reported a high prevalence of cardiomyopathy, this prevalence is much lower in cardiac magnetic resonance imaging-based studies. Myocardial hypertrophy in acromegaly is due to a homogeneous increase in the intracellular myocardial mass and extracellular myocardial matrix and improves following successful treatment through intracellular changes. Intramyocardial water retention or ectopic lipid accumulation might not be of relevant concern. Successful treatment significantly improves myocardial morphology, as well as cardiovascular risk factors. In addition to GH/IGF-I-lowering therapy, the diagnosis and treatment of cardiovascular complications is crucial for the successful management of acromegaly.

Practical therapeutic approach in the management of diabetes mellitus secondary to Cushing's syndrome, acromegaly and neuroendocrine tumours

Cushing's syndrome, acromegaly and neuroendocrine disorders are characterized by an excess of counterregulatory hormones, able to induce insulin resistance and glucose metabolism disorders at variable degrees and requiring immediate treatment, until patients are ready to undergo surgery. This review focuses on the management of diabetes mellitus in endocrine disorders related to an excess of counterregulatory hormones. Currently, the landscape of approved agents for treatment of diabetes is dynamic and is mainly patient-centred and not glycaemia-centred. In addition, personalized medicine is more and more required to provide a precise approach to the patient's disease. For this reason, we aimed to define a practical therapeutic algorithm for management of diabetes mellitus in patients with glucagonoma, pheochromocytoma, Cushing's syndrome and acromegaly, based on our practical experience and on the physiopathology of the specific endocrine disease taken into account. This document is addressed to all specialists who approach patients with diabetes mellitus secondary to endocrine disorders characterized by an excess of counterregulatory hormones, in order to take better care of these patients. Care and control of diabetes mellitus should be one of the primary goals in patients with an excess of counterregulatory hormones requiring immediate and aggressive treatment.

Uric acid levels correlate with disease activity in growth hormone-secreting pituitary adenoma patients

Objective

Few studies reported the effects of growth hormone-secreting pituitary adenoma (GHPA) on uric acid (UA) metabolism and the relationship between growth hormone (GH)/insulin-like growth factor-1 (IGF-1) levels and UA are controversial. This study aimed to evaluate the relationship between IGF-1 and UA in patients with GHPA and to further clarify whether UA levels are associated with GHPA disease activity by follow-up.

Methods

A longitudinal study of 424 GHPA patients presenting to Beijing Tiantan Hospital, Capital Medical University between January 2015 and January 2023 was conducted. Spearman's correlation tests were performed to examine the relationship between IGF-1 and UA at baseline. Univariate and multivariate linear regression analysis was conducted to investigate the independent association between UA and IGF-1. Changes in postoperative IGF-1 and UA levels were followed prospectively, and the differences in UA levels between the biochemical remission and nonremission groups were compared.

Results

At baseline, male patients, the lower the age, the higher the IGF-1 and body mass index (BMI), and the higher the UA levels. IGF-1 was significantly associated with UA after controlling for sex, age, and BMI (r = 0.122, P = 0.012). In adjusted multiple linear regression analysis, IGF-1 was independently associated with UA, and UA levels increased significantly with increasing IGF-1. During postoperative follow-up, UA decreased gradually as IGF-1 levels decreased. At 12 months postoperatively, UA levels were significantly lower in the biochemical remission group than in the nonremission group (P = 0.038).

Conclusions

In patients with GHPA, UA levels are associated with disease activity. Changes in UA levels should be taken into account in the comprehensive treatment of GHPA, patients presenting with HUA should be given lifestyle guidance and appropriate urate-lowering treatment according to their condition to better improve their prognosis.

The Effect and Potential Mechanism Analysis of Growth Hormone-Secreting Pituitary Adenomas on Thyroid Function

OBJECTIVE

Current studies on the effect of high growth hormone (GH)/insulin-like growth factor (IGF)-1 on thyroid function are inconsistent. The aim was to explore the effect and potential mechanism of high GH/IGF-1 on thyroid function by analyzing the changes of thyroid function in patients with growth hormone-secreting pituitary adenoma (GHPA).

METHODS

This was a retrospective cross-sectional study. Demographic and clinical data of 351 patients with GHPA who were first admitted to Beijing Tiantan Hospital, Capital Medical University, from 2015 to 2022 were collected to analyze the relationship between high GH/IGF-1 levels and thyroid function.

RESULTS

GH was negatively correlated with total thyroxine (TT4), free thyroxine (FT4), and thyroid-stimulating hormone (TSH). IGF-1 was positively correlated with total triiodothyronine (TT3), free triiodothyronine (FT3), and FT4 and negatively correlated with TSH. Insulin-like growth factor-binding protein (IGFBP)-3 was positively correlated with TT3, FT3, and FT3:FT4 ratio. The FT3, TT3, TSH, and FT3:FT4 ratio of patients with GHPA and diabetes mellitus (DM) were significantly lower than those with GHPA but without DM. With the increase of tumor volume, thyroid function gradually decreased. GH and IGF-1 were correlated negatively with age in patients with GHPA.

CONCLUSION

The study emphasized the complex interaction between the GH and the thyroid axes in patients with GHPA and highlighted the potential effect of glycemic status and tumor volume on thyroid function.

Long-term Outcome of Body Composition, Ectopic Lipid, and Insulin Resistance Changes With Surgical Treatment of Acromegaly

Context

Acromegaly presents a unique pattern of lower adiposity and insulin resistance in active disease but reduction in insulin resistance despite a rise in adiposity after surgery. Depot-specific adipose tissue masses and ectopic lipid are important predictors of insulin resistance in other populations, but whether they are in acromegaly is unknown. Long-term persistence of body composition changes after surgery is unknown.

Objective

To determine how depot-specific body composition and ectopic lipid relate to insulin resistance in active acromegaly and whether their changes with surgery are sustained long-term.

Methods

Cross-sectional study in patients with active acromegaly and longitudinal study in newly diagnosed patients studied before and in long-term follow-up, 3 (1-8) years (median, range), after surgery. Seventy-one patients with active acromegaly studied cross-sectionally and 28 with newly diagnosed acromegaly studied longitudinally. Main outcome measures were visceral (VAT), subcutaneous (SAT), and intermuscular adipose tissue masses by whole-body magnetic resonance imaging; intrahepatic lipid (IHL) by proton magnetic resonance spectroscopy; insulin resistance measures derived from fasting; and oral glucose tolerance test insulin and glucose levels.

Results

SAT and insulin-like growth factor 1 level, but not VAT or IHL, were independent predictors of insulin resistance in active acromegaly. VAT, SAT, and IHL gains were sustained long-term after surgery. VAT mass rise with surgery correlated inversely with rise in QUICKI while SAT rise correlated with fall in the Homeostatic Model Assessment score.

Conclusion

SAT and disease activity are important predictors of insulin resistance in active acromegaly. Adiposity gains are sustained long-term after surgical treatment and impact on the accompanying improvement in insulin resistance.

The Impact of Westernization on the Insulin/IGF-I Signaling Pathway and the Metabolic Syndrome: It Is Time for Change

The metabolic syndrome is a cluster of overlapping conditions resulting in an increased incidence of type 2 diabetes, cardiovascular disease, and cancer. In the last few decades, prevalence of the metabolic syndrome in the Western world has reached epidemic proportions and this is likely due to alterations in diet and the environment as well as decreased physical activity. This review discusses how the Western diet and lifestyle (Westernization) has played an important etiological role in the pathogenesis of the metabolic syndrome and its consequences by exerting negative effects on activity of the insulin-insulin-like growth factor-I (insulin-IGF-I) system. It is further proposed that interventions that normalize/reduce activity of the insulin-IGF-I system may play a key role in the prevention and treatment of the metabolic syndrome. For successful prevention, limitation, and treatment of the metabolic syndrome, the focus should be primarily on changing our diets and lifestyle in accordance with our genetic make-up, formed in adaptation to Paleolithic diets and lifestyles during a period of several million years of human evolution. Translating this insight into clinical practice, however, requires not only individual changes in our food and lifestyle, starting in pediatric populations at a very young age, but also requires fundamental changes in our current health systems and food industry. Change is needed: primary prevention of the metabolic syndrome should be made a political priority. New strategies and policies should be developed to stimulate and implement behaviors encouraging the sustainable use of healthy diets and lifestyles to prevent the metabolic syndrome before it develops.

The potential utility of the SAGIT instrument in the clinical assessment of patients with acromegaly, a large single-centre study

SAGIT is an instrument created for the clinical assessment of acromegaly. Our objective was to test the usefulness of this tool in assessing disease activity of acromegalic patients in a single centre of Poznan, Poland using a retrospective study. Medical records of patients with acromegaly hospitalised at the Department of Endocrinology, Metabolism and Internal Medicine of Poznan University of Medical Sciences in Poland between January 2015 and December 2020 were analysed. SAGIT scores were assessed according to each patient's clinical and biochemical data. The results show that SAGIT scores were higher in treatment-naïve patients and the lowest in controlled patients. There were positive correlations between SAGIT scores and concentrations of calcium, phosphorus, HbA1C levels, and tumour invasiveness at the time of diagnosis. However, parameters such as age, vitamin D concentration, and time from diagnosis showed an inverse relationship with the SAGIT score. In ROC curve analysis, SAGIT scores of 5 or less discriminated controlled patients from uncontrolled (p < 0.0001, sensitivity 76.7%, specificity 78.5%, AUC 0.867). Also, SAGIT higher than 6 indicated for treatment start or escalation (p < 0.0001, sensitivity 80.88%, specificity 77.59%, AUC 0.866). Lack of signs and symptoms (S = 0) could not discriminate between controlled and uncontrolled disease, but predicted therapy maintenance (p < 0.0004, sensitivity 59.5%, specificity 58.2%, AUC 0.604). In conclusion, The SAGIT instrument is easy to use even when completed in the retrospective medical record review. It can be useful for distinguishing clinical stages of acromegaly and in decision-making.

Polycystic ovary syndrome preceding the diagnosis of acromegaly: a retrospective study in 97 reproductive-aged women

BACKGROUND

Acromegaly is a disease of growth hormone excess that results in enlargement of extremities, abnormal glucose and lipid metabolism, and gonadal disruption. Manifestations of the disease are insidious and typically lead to a diagnostic delay of 7-10 years. Classically the polycystic ovary syndrome (PCOS) phenotype is described in women with irregular menses, clinical or biochemical evidence of androgen excess, and/or multiple ovarian follicles on pelvic ultrasonography. Women with acromegaly may present with some or all of these symptoms. Our objective was to evaluate the prevalence of PCOS in patients with acromegaly and to determine if diagnosis of PCOS results in a delay in diagnosing acromegaly.

METHODS

Using patient databases at two academic health centers, we identified 97 premenopausal women aged 18-49 years old presenting with acromegaly. Data were collected regarding pelvic sonography and reproductive history, including the diagnosis of PCOS. Patients carrying the diagnosis of PCOS before their diagnosis of acromegaly were identified and the remaining patients were screened using the Rotterdam criteria to identify additional patients meeting the criteria for PCOS prior to their diagnosis of acromegaly.

RESULTS

Mean age of the population (n = 97) at the time of diagnosis of acromegaly was 33.4 ± 7.5 years (SD). Thirty-three percent of patients (n = 32) either carried a diagnosis of PCOS or met diagnostic criteria for PCOS before their diagnosis of acromegaly. In the subset of patients in whom data on symptom onset were available, those who met criteria for PCOS were diagnosed with acromegaly a median of 5 years [4, 9] after the onset of symptoms compared to 2 years [0.92, 3] (p =  0.006) in the patients who did not meet criteria for PCOS.

CONCLUSIONS

Our data demonstrate a high prevalence of signs and symptoms of PCOS in reproductive-aged women with acromegaly and a longer time to diagnosis in women who meet the clinical criteria for PCOS. As screening for acromegaly is relatively simple and done with measurement of a random, non-fasting IGF-1 level that can be drawn at any time during the menstrual cycle, screening patients with PCOS for acromegaly may lessen the delay in diagnosis for reproductive-aged women with this disease.

Serum biomarkers of colonic polyps in patients with acromegaly: a meta-analysis and systematic review

PURPOSE

In the past few decades, acromegaly and colonic polyps have been associated with an increased risk of colorectal cancer. Previous studies highlighted the importance of serum biomarkers of colonic polyps in patients with acromegaly.

METHODS

We reviewed studies on serum biomarkers of colonic polyps in patients with acromegaly, published on PubMed, Embase, Cochrane Library, Medline, and Chinese databases from January 1, 1966, to May 8, 2022. Meta-analysis and systematic review were conducted using Stata MP 14.0.

RESULTS

Eight articles were included in this study. The mean (standard deviation) concentrations of serum biomarkers for acromegaly with and without colorectal polyps were extracted from these studies. Meta-analysis results showed that, compared to patients without colonic polyps, the levels of insulin-like growth factor-1 × upper limit of normal range (IGF-1 × ULN) and fasting insulin were significantly increased; while the levels of growth hormone (GH) were significantly decreased in patients with acromegaly and colonic polyps (IGF-1 × ULN: SMD 0.23; 95% CI 0.03-0.42, p < 0.05) (fasting insulin: SMD 0.95; 9 5% CI 0.11-1.8, p < 0.05) (GH: SMD - 0.25; 95% CI - 0.41 to - 0.08, p < 0.05). IGF-1 and FPG levels did not differ significantly (IGF-1: SMD -0.03; 95% CI - 0.22 to 0.17, p > 0.05) (FPG: SMD 0.14; 95% CI - 0.23 to 0.52, p > 0.05). The systematic review results suggest no significant differences in hemoglobin A1C, TSH, free thyroxine, FT4, T3, PRL, total cholesterol, HDL, LDL, fibrinogen, clathrate antigen, serum antigen 19-9, and α-fetoprotein levels, but serum Klotho levels.

CONCLUSION

We present the first meta-analysis and systematic review of serum biomarkers in patients with acromegaly or colonic polyps. The prevalence of colonic lesion polyps, is associated with higher IGF-1 × ULN levels, higher insulin levels in acromegaly. Further research is required to confirm GH and serum soluble Klotho levels as biomarkers of colonic polyps. When IGF-1 × ULN, fasting insulin levels change in patients with acromegaly, the occurrence of colonic polyps should be monitored. Early detection may reduce the possibility of developing malignant colon neoplasms.

Ectopic lipid deposition and insulin resistance in patients with GH disorders before and after treatment

OBJECTIVES

Insulin resistance is associated with ectopic lipid deposition. Growth hormone (GH) status also modulates ectopic lipid accumulation, but how this associates with insulin resistance in patients with GH disorders is not well established.

DESIGN AND METHODS

Twenty-one patients diagnosed with acromegaly and 12 patients with adult GH deficiency (GHD) were studied at diagnosis and after treatment. A reference group of 12 subjects was included. Each study day comprised assessment of body composition with dual-energy X-ray absorptiometry, ectopic lipid deposition in the liver by MR spectroscopy, and Homeostatic Model Assessment for Insulin Resistance (HOMA-IR).

RESULTS

Disease control of acromegaly decreased lean body mass (LBM) (P < .000) and increased the percentage of total body fat (TBF) (P < .000). GH replacement increased LBM in the GHD patients (P = .007) and decreased the percentage of TBF (P = .010). The intrahepatic lipid (IHL) content increased after disease control in acromegaly (P = .004), whereas IHL did not change significantly after GH replacement in GHD (P = .34). Insulin resistance (HOMA-IR) improved after disease control of acromegaly (P < .000) and remained unaltered after GH replacement in the GHD patients (P = .829).

CONCLUSIONS

GH status is a significant modulator of body composition and insulin sensitivity.GH excess reduces total fat mass and intrahepatic lipid content together with induction of insulin resistance.The data support the notion that GH-induced insulin resistance is unassociated with hepatic lipid accumulation.

Insulin Requirements in Untreated Acromegaly: From 200 to 0

We describe a patient with acromegaly presenting in diabetic ketoacidosis who was able to achieve euglycemia despite discontinuation of all antihyperglycemic therapy prior to surgical or medical treatment for his acromegaly. No previous cases of acromegaly presenting in diabetic ketoacidosis have reported glycemic normalization without antihyperglycemic therapy prior to acromegaly treatment. Our case highlights this unique outcome and postulates that pancreatic β-cell resiliency may be influential on insulin resistance since our patient achieved euglycemia despite a persistent state of excess growth hormone and insulin-like growth factor-1. Our case further emphasizes that consideration for acromegaly should be given in patients presenting with severe insulin resistance and pertinent medical history and physical examination features, and it emphasizes the dramatic range of insulin requirements in patients with acromegaly.

Ectopic lipid metabolism in anterior pituitary dysfunction

Over the past decades, adapted lifestyle and dietary habits in industrialized countries have led to a progress of obesity and associated metabolic disorders. Concomitant insulin resistance and derangements in lipid metabolism foster the deposition of excess lipids in organs and tissues with limited capacity of physiologic lipid storage. In organs pivotal for systemic metabolic homeostasis, this ectopic lipid content disturbs metabolic action, thereby promotes the progression of metabolic disease, and inherits a risk for cardiometabolic complications. Pituitary hormone syndromes are commonly associated with metabolic diseases. However, the impact on subcutaneous, visceral, and ectopic fat stores between disorders and their underlying hormonal axes is rather different, and the underlying pathophysiological pathways remain largely unknown. Pituitary disorders might influence ectopic lipid deposition indirectly by modulating lipid metabolism and insulin sensitivity, but also directly by organ specific hormonal effects on energy metabolism. In this review, we aim to I) provide information about the impact of pituitary disorders on ectopic fat stores, II) and to present up-to-date knowledge on potential pathophysiological mechanisms of hormone action in ectopic lipid metabolism.

Prediabetes and mild hepatosteatosis are associated with blunted cortisol response to glucagon but not to growth hormone

BACKGROUND

Although there is a close relationship between cortisol and growth hormone (GH) levels, glucose intolerance and hepatosteatosis, changes in GH and the hypothalamo-pituitary-adrenal (HPA) axis were not previously studied in prediabetes. The main purpose of the present study was to assess changes in GH and HPA axis and their relationship with hepatosteatosis in prediabetic patients.

METHODS

Forty prediabetic patients, with body-mass index (BMI) 25-35kg/m², and 23 healthy individuals, with normal glucose tolerance and similar age and BMI, were included. The 75g oral glucose tolerance test and glucagon stimulation test (GST) were used.

RESULTS

No significant differences were detected between prediabetic patients and healthy individuals in terms of insulin-like growth factor-1 (IGF-1), insulin-like growth factor-binding protein-3 (IGFBP-3), IGF-1/IGFBP3 ratio or adrenocorticotropic hormone (ACTH). GH responses to GST did not differ between groups. On the other hand, peak cortisol and area under the curve (AUC) _(cortisol) response on GST were significantly lower in prediabetic patients. Both peak GH and AUC _(GH) response on GST correlated negatively with waist circumference and body weight. The degree of hepatosteatosis correlated negatively with peak cortisol, GH, AUC (cortisol) and AUC (GH) response on GST.

CONCLUSION

Cortisol response to GST is decreased in prediabetic patients, with relatively well conserved GH response. This suggests altered HPA axis responsiveness in prediabetes, as is known in diabetes. Thus, HPA axis changes in patients with diabetes probably start before the development of diabetes as such.

Impairment in insulin secretion without changes in insulin resistance explains hyperglycemia in patients with acromegaly treated with pasireotide LAR

Objective

Pasireotide is a second-generation somatostatin receptor ligand (SRL) used for treating acromegaly. Its clinical use is limited by adverse effects on glucose homeostasis. The aim of this study was to evaluate longitudinal changes in beta-cell function and insulin sensitivity associated with pasireotide in patients not controlled by first-generation SRLs.

Design

We performed a retrospective study.

Methods

The efficacy (growth hormone (GH)/insulin-like growth factor (IGF-1) concentrations; tumor size) and effect on glucose homeostasis were analyzed in 33 patients. Longitudinal data on oral glucose tolerance tests were available before, shortly (mean ± s.d., 6.1 ± 3.8 months) and long term (24.4 ± 11.1 months) after initiation of pasireotide in 14 patients. Insulin secretion (insulinogenic index; disposition index) and insulin sensitivity were calculated by validated indices.

Results

Pasireotide-induced diabetes occurred in 12 patients (36%). It was mediated by impaired insulin secretion, which occurred shortly after initiation of treatment and then remained stable on long term (insulinogenic index, median (min; max), 80 (12; 542) vs 16 (6.4; 101) vs 25 (3.7; 396) pmol/mmol, respectively; P = 0.028; disposition index, 1.45 (0.42; 4.88) vs 0.53 (0.17; 2.63) vs 0.60 (0.22; 1.71), respectively; P = 0.024). No significant changes in insulin sensitivity were observed, despite a marked reduction of GH/IGF-1 concentrations. Older age and a worse glycemic control at baseline were the strongest predictors for hyperglycemia and the need for antidiabetic treatment.

Conclusion

Worsening of glycemic control during pasireotide therapy is caused by an impaired insulin secretion, whereas insulin sensitivity is not affected. These findings might be important for the choice of antidiabetic treatment for pasireotide-induced hyperglycemia.

Significance statement

Pasireotide, a second-generation SRL used for treating acromegaly, may be associated with glucose metabolism impairment. In a retrospective study of 33 patients, we observed that treatment with pasireotide was associated with normalization of serum IGF-1 in almost 60% of patients, but one-third of patients developed diabetes. In the patients who stopped pasireotide because of hyperglycemia, HbA1c promptly decreased. Longitudinal data in 14 patients show that diabetes is mediated by impaired insulin secretion, which occurred shortly and then remained stable on long term, while no significant changes in insulin sensitivity were observed, despite a marked reduction of GH/IGF-1 concentrations. Older age and a worse glycemic control at baseline were the strongest predictors for hyperglycemia.

ACROBAT Edge: Safety and efficacy of switching injected SRLs to oral paltusotine in patients with acromegaly

CONTEXT

Paltusotine is a once-daily, oral, non-peptide small-molecule somatostatin receptor type 2 (SST2) agonist in clinical development for treatment of acromegaly.

OBJECTIVE

To evaluate change in IGF-I levels in patients switched from octreotide LAR or lanreotide depot monotherapy to paltusotine.

DESIGN

Phase 2, open-label, prospective, multicenter, multinational, non-randomized, single-arm exploratory study in which dosage up-titrations were performed in a double-blinded manner.

SETTING

26 global sites.

PARTICIPANTS

Patients with acromegaly switched to paltusotine from injected SRL-based therapy.

INTERVENTIONS

Patients received 13-week treatment with once-daily oral paltusotine (10-40 mg/day).

MAIN OUTCOME MEASURES

Primary endpoint was change from baseline to week 13 in IGF-I for patients who switched from long-acting octreotide or lanreotide monotherapy to paltusotine (Group 1). All patients underwent a 4-week paltusotine washout at end of treatment period (weeks 13-17). IGF-I, GH, patient reported outcome, and safety data were collected.

RESULTS

Forty-seven patients enrolled. In Group 1 (n = 25), IGF-I and GH showed no significant change between SRL baseline and end of paltusotine treatment at week 13 (median change in IGF-I = -0.03×upper limit of normal [ULN], P = 0.6285; GH = -0.05 ng/mL, P = 0.6285). IGF-I and GH rose significantly in the 4 weeks after withdrawing paltusotine (median change in IGF-I = 0.55×ULN, P < 0.0001 [median increase 39%]; GH = 0.72 ng/mL, P < 0.0001 [109.1% increase]). No patients discontinued due to adverse events; no treatment-related serious adverse events were reported.

CONCLUSIONS

These results suggest once daily, oral paltusotine is effective in maintaining IGF-I values in patients with acromegaly who switched from injected SRLs. Paltusotine was well tolerated with a safety profile consistent with other SRLs.

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.

Risk of Neurodegenerative Diseases in Patients With Acromegaly: A Cohort Study

BACKGROUND AND OBJECTIVES

A few recent studies have reported an association between insulin-like growth factor-1 (IGF-1) and neurodegenerative disease, but there was no report on any association between acromegaly and neurodegenerative disease. We investigated whether the risk of Alzheimer disease (AD), Parkinson disease, and other neurodegenerative diseases was increased among patients with acromegaly using nationwide data of Korea.

METHODS

We studied the association between acromegaly and Parkinson disease and dementia in 1,611 patients with acromegaly and controls (age-matched and sex-matched 8,055 participants with no diagnosis of acromegaly) from the National Health Insurance System database between 2006 and 2016 with a mean follow-up period of 7.34 years. Cox proportional hazards regression analysis was used to assess the risk of all outcomes in patients with acromegaly compared with controls with adjusting for age, sex, household income, place, type 2 diabetes, hypertension, and dyslipidemia.

RESULTS

The average age of the patients with acromegaly and the controls was 54.16 years (40.4% men). The incidence rate of Parkinson disease in patients with acromegaly (1.54 per 1,000 person-years) was significantly higher than that in the control group (0.55 per 1,000 person-years) (log-rank test p = 0.001). Acromegaly was associated with a higher risk of Parkinson disease (hazard ratio [HR] = 2.609, 95% CI: 1.410-2.609) than the control. In addition, acromegaly was associated with a higher risk of all-cause dementia (HR = 2.299, 95% CI: 1.362-3.881), Alzheimer disease (HR = 2.228, 95% CI: 1.191-4.168), and non-AD dementia (HR = 6.553, 95% CI: 1.754-24.482) than the control during the first 3 years after diagnosis and treatment. In subgroup analysis, diabetes was associated with higher risk of all-cause dementia (P for interaction = 0.028) in patients with acromegaly compared with controls.

DISCUSSION

Our study results suggest that acromegaly is associated with neurodegenerative disease. Further study is needed on the association between IGF-1/growth hormone level and neurodegenerative disease.

Growth Hormone and Counterregulation in the Pathogenesis of Diabetes

PURPOSE OF REVIEW

Canonical growth hormone (GH)-dependent signaling is essential for growth and counterregulatory responses to hypoglycemia, but also may contribute to glucose homeostasis (even in the absence of hypoglycemia) via its impact on metabolism of carbohydrates, lipids and proteins, body composition, and cardiovascular risk profile. The aim of this review is to summarize recent data implicating GH action in metabolic control, including both IGF-1-dependent and -independent pathways, and its potential role as target for T2D therapy.

RECENT FINDINGS

Experimental blockade of the GHR can modulate glucose metabolism. Moreover, the soluble form of the GH receptor (GHR, or GHBP) was recently identified as a mediator of improvement in glycemic control in patients with T2D randomized to bariatric surgery vs. medical therapy. Reductions in GHR were accompanied by increases in plasma GH, but unchanged levels of both total and free IGF-1. Likewise, hepatic GHR expression is reduced following both RYGB and VSG in rodents. Emerging data indicate that GH signaling is important for regulation of long-term glucose metabolism in T2D. Future studies will be required to dissect tissue-specific GH signaling and sensitivity and their contributions to systemic glucose metabolism.

The acromegaly lipodystrophy

Growth hormone (GH) and insulin-like growth factor 1 (IGF-1) are essential to normal growth, metabolism, and body composition, but in acromegaly, excesses of these hormones strikingly alter them. In recent years, the use of modern methodologies to assess body composition in patients with acromegaly has revealed novel aspects of the acromegaly phenotype. In particular, acromegaly presents a unique pattern of body composition changes in the setting of insulin resistance that we propose herein to be considered an acromegaly-specific lipodystrophy. The lipodystrophy, initiated by a distinctive GH-driven adipose tissue dysregulation, features insulin resistance in the setting of reduced visceral adipose tissue (VAT) mass and intra-hepatic lipid (IHL) but with lipid redistribution, resulting in ectopic lipid deposition in muscle. With recovery of the lipodystrophy, adipose tissue mass, especially that of VAT and IHL, rises, but insulin resistance is lessened. Abnormalities of adipose tissue adipokines may play a role in the disordered adipose tissue metabolism and insulin resistance of the lipodystrophy. The orexigenic hormone ghrelin and peptide Agouti-related peptide may also be affected by active acromegaly as well as variably by acromegaly therapies, which may contribute to the lipodystrophy. Understanding the pathophysiology of the lipodystrophy and how acromegaly therapies differentially reverse its features may be important to optimizing the long-term outcome for patients with this disease. This perspective describes evidence in support of this acromegaly lipodystrophy model and its relevance to acromegaly pathophysiology and the treatment of patients with acromegaly.

The Modulatory Role of Growth Hormone in Inflammation and Macrophage Activation

Inflammation is a body's response to remove harmful stimuli and heal tissue damage, which is involved in various physiology and pathophysiology conditions. If dysregulated, inflammation may lead to significant negative impacts. Growth hormone (GH) has been shown responsible for not only body growth but also critical in the modulation of inflammation. In this review, we summarize the current clinical and animal studies about the complex and critical role of GH in inflammation. Briefly, GH excess or deficiency may lead to pathological inflammatory status. In inflammatory diseases, GH may serve as an inflammatory modulator to control the disease progression and promote disease resolution. The detailed mechanisms and signaling pathways of GH on inflammation, with a focus on the modulation of macrophage polarization, are carefully discussed with potential direction for future investigations.

Mice with gene alterations in the GH and IGF family

Much of our understanding of GH's action stems from animal models and the generation and characterization of genetically altered or modified mice. Manipulation of genes in the GH/IGF1 family in animals started in 1982 when the first GH transgenic mice were produced. Since then, multiple laboratories have altered mouse DNA to globally disrupt Gh, Ghr, and other genes upstream or downstream of GH or its receptor. The ability to stay current with the various genetically manipulated mouse lines within the realm of GH/IGF1 research has been daunting. As such, this review attempts to consolidate and summarize the literature related to the initial characterization of many of the known gene-manipulated mice relating to the actions of GH, PRL and IGF1. We have organized the mouse lines by modifications made to constituents of the GH/IGF1 family either upstream or downstream of GHR or to the GHR itself. Available data on the effect of altered gene expression on growth, GH/IGF1 levels, body composition, reproduction, diabetes, metabolism, cancer, and aging are summarized. For the ease of finding this information, key words are highlighted in bold throughout the main text for each mouse line and this information is summarized in Tables 1, 2, 3 and 4. Most importantly, the collective data derived from and reported for these mice have enhanced our understanding of GH action.

Body Composition in Acromegaly According to Disease Activity - Performance of Dual X-Ray Absorptiometry and Multifrequency Bioelectrical Impedance Analysis

INTRODUCTION

the present study aims to evaluate body composition and its relationship with hormonal control in acromegaly, also comparing the performance of Bioelectrical impedance analysis (BIA), a more accessible method, with dual X-ray absorptiometry (DXA), technology frequently used in current studies.

METHODS

we studied 28 patients (78% female) of whom 13 with active disease, mean age was 52.11 ± 12.53 years; 64% had high blood pressure (HBP) and 50% had type 2 diabetes (T2D).

RESULTS

Although patients with controlled disease had lower serum GH (1.2 ± 1.68µg/L vs 6.61 ± 6.40µg/L, p=0.001) and IGF-1 (158.89 ± 54.53ng/mL and 503.31 ± 253.25ng/mL, p<0.001), they did not differ in body composition: percentage of fat mass: 36.13 ± 11.84% vs 37.73 ± 8.76%, p=0.691 for BIA and 37.10 ± 10.21% vs 37.89 ± 7.32%, p=0.819 for DXA; muscle mass parameters, BIA: FFMI 18.68 ± 2.38kg/m²vs 19.14 ± 1.59kg/m², p=0.560; SMI 10.17 ± 1.39kg/m²vs 10.53 ± 1.01kg/m², p=0.438; DXA: Baumgartner 7.99 ± 1.43kg/m²vs 8.02 ± 1.24kg/m², p=0.947, respectively for controlled and active disease. Patients with controlled acromegaly had lower fasting glucose (110.33 ± 55.48mg/dL vs 129.77 ± 40.17mg/dL, p=0.033) and were less likely to have persistent T2D (28.6 vs 71.4%, p=0.008) and HBP (38.9 vs 61.1%, p=0.049). There were strong positive correlations between BIA and DXA for fat mass (r=0.929, p<0.001) and muscle mass parameters: SMI X Baumgartner: r=0.890, p<0.001; and FFMI X Baumgartner: r=0.868, p<0.001.

CONCLUSION

our data showed similar results in body composition assessment by BIA and DXA, with good correlation between the methods, regardless of the hormonal status of acromegaly. Furthermore, in patients with adequate hormonal control, there was preservation of muscle mass and a lower prevalence of metabolic comorbidities, such as T2D and HBP.

Continuous Glucose Monitoring System in Acromegalic Patients: Possible Role in the Assessment of Glycemia Control

BACKGROUND

Acromegaly is characterized by an insulin resistance condition. There is a significant difference between the different types of therapy in relation to the glycometabolic framework. The blinded continuous glucose monitoring system (CGMS), throughout a period of maximum 6 days for a total of 288 glycemic registrations per day, identifies glycemic excursions and could constitute a valid device to understand the 24-hour glycemic profiles.

AIM OF THE STUDY

To compare the oral glucose tolerance test (OGTT) and CGMS methods in acromegalic patients to evaluate their glycemic profiles, in relation to different treatments for acromegaly.

METHODS

Thirty-five acromegalic patients were divided into 18 somatostatin analogs (SSA), 9 pegvisomant, and 8 successfully surgically treated. A 72-hour CGM was performed and, immediately after, an OGTT.

RESULTS

Results obtained from OGTT: 11/35 impaired fasting glucose, 6/35 impaired glucose tolerance, and 4/35 diabetes mellitus. A positive significant correlation was demonstrated between the OGTT peak and CGM peak in all of the patients, CGM peak of patients treated with SSA and those surgically treated, OGTT average and CGM area under concentration-time curve (AUC) for hyperglycemia of patients treated with SSA and those surgically treated, and CGM AUC for hyperglycemia of patients treated with SSA and those surgically treated.

CONCLUSIONS

Our results show a significantly higher response in terms of mean and peak OGTT in patients treated with SSA, both compared to the CGM study, and compared to the group of patients receiving pegvisomant. The CGM system could represent an instrument for the evaluation of the glycemic trend of acromegalic patients.

Towards Understanding the Direct and Indirect Actions of Growth Hormone in Controlling Hepatocyte Carbohydrate and Lipid Metabolism

Growth hormone (GH) is critical for achieving normal structural growth. In addition, GH plays an important role in regulating metabolic function. GH acts through its GH receptor (GHR) to modulate the production and function of insulin-like growth factor 1 (IGF1) and insulin. GH, IGF1, and insulin act on multiple tissues to coordinate metabolic control in a context-specific manner. This review will specifically focus on our current understanding of the direct and indirect actions of GH to control liver (hepatocyte) carbohydrate and lipid metabolism in the context of normal fasting (sleep) and feeding (wake) cycles and in response to prolonged nutrient deprivation and excess. Caveats and challenges related to the model systems used and areas that require further investigation towards a clearer understanding of the role GH plays in metabolic health and disease are discussed.

Glucose metabolism outcomes in acromegaly patients on treatment with pasireotide-LAR or pasireotide-LAR plus Pegvisomant

INTRODUCTION

Disorders of glucose metabolism are a serious acromegaly comorbidity and may be differently impacted by medical treatments of acromegaly. In this retrospective longitudinal multicenter study, we investigated the outcome of glucose metabolism and its predictors in patients treated with Pasireotide LAR (PAS-LAR) alone or in combination with Pegvisomant (PAS-LAR + Peg-V).

SUBJECTS AND METHODS

Acromegaly patients treated continously with PAS-LAR or PAS-LAR + Peg-V for at least 6 months.

RESULTS

Forty patients (25 females, 15 males) were enrolled. At last visit, 27/40 patients (67.5%) reached biochemical control of acromegaly. Overall, glucose metabolism improved in 3 (all in PAS-LAR + Peg-V; 7.5%), worsened in 26 (65%) and remained unchanged in 11 patients (27.5%). Glucose metabolism worsened in 25 patients (73.5%) treated with PAS-LAR and in a single patient (16.7%) treated with PAS-LAR + Peg-V (p < 0.001). Among patients treated with Pas-LAR alone, GH at baseline was higher in those with worsening of glucose metabolism (p = 0.04) as compared to those with stable glucose status. A significantly higher reduction of HbA1c was observed in patients treated with PAS-LAR + Peg-V, as compared with those treated with PAS-LAR alone (p = 0.005).

CONCLUSIONS

Our data confirmed that glucose metabolism in patients treated with PAS-LAR is often worsened, and may be predicted by entity of baseline GH hypersecretion and by the dose of PAS-LAR. Moreover, our data, although limited by small numbers, may suggest that the combination treatment PAS-LAR + Peg-V can improve glucose homeostasis in selected patients.

Regulation of GH and GH Signaling by Nutrients

Growth hormone (GH) and insulin-like growth factor-1 (IGF-I) are pleiotropic hormones with important roles in lifespan. They promote growth, anabolic actions, and body maintenance, and in conditions of energy deprivation, favor catabolic feedback mechanisms switching from carbohydrate oxidation to lipolysis, with the aim to preserve protein storages and survival. IGF-I/insulin signaling was also the first one identified in the regulation of lifespan in relation to the nutrient-sensing. Indeed, nutrients are crucial modifiers of the GH/IGF-I axis, and these hormones also regulate the complex orchestration of utilization of nutrients in cell and tissues. The aim of this review is to summarize current knowledge on the reciprocal feedback among the GH/IGF-I axis, macro and micronutrients, and dietary regimens, including caloric restriction. Expanding the depth of information on this topic could open perspectives in nutrition management, prevention, and treatment of GH/IGF-I deficiency or excess during life.

Transcriptome profiling of insulin sensitive tissues from GH deficient mice following GH treatment

PURPOSE

Most studies that have examined the transcriptional response to GH have been performed with a single tissue. Thus, the current study performed RNASeq across three insulin-sensitive tissues of GH-treated GH deficient (GHKO) mice.

METHODS

GHKO mice were injected with recombinant human GH (hGH) or vehicle daily for 5 days and adipose, liver, and muscle tissues were collected 4 h after the final injection. RNA was isolated from the tissues and sequenced. Genes that were differentially expressed between GH and vehicle treatments were further analyzed. Enrichment analysis and topology-aware pathway analysis were performed.

RESULTS

GHKO mice treated with hGH had expected phenotypic alterations, with increased body, fat, fluid, liver, and muscle mass, and increased serum IGF-1 and insulin. 55 Genes were differentially expressed in all three tissues, including the canonical GH targets Igf1, Igfals, and Cish. Enrichment analysis confirmed the canonical GH response in select tissues, such as cell proliferation, metabolism, and fibrosis. The JAK/STAT pathway was the only pathway significantly altered in all three tissues.

CONCLUSIONS

As expected, GH caused expression changes of many known target genes, although new candidate GH targets were identified. Liver and muscle appear to be more GH sensitive than adipose tissue due to the larger number of DEG and pathways significantly altered, but adipose still has a characteristic GH response. The diversity of changes uncovered in all three tissues after 5 days of GH treatment highlights the multiplicity of GH's effects in its target tissues.

Repeat Epidural Injections of SP-102 (Dexamethasone Sodium Phosphate Injectable Gel) in Subjects with Lumbosacral Radiculopathy

Purpose

SP-102 is a novel epidural steroid injection (ESI) formulation of 10 mg dexamethasone sodium phosphate in a viscous gel solution. Repeat dosing of ESIs is possible if required for pain relief, but with consideration of hypothalamic–pituitary–adrenal (HPA) axis suppression from prolonged systemic exposure. This phase I/II study investigated the effect of initial and repeat SP-102 injections on HPA suppression and analgesia.

Methods

Subjects with lumbosacral radiculopathy received an initial epidural SP-102 injection (T1) on day 1, followed by a repeat injection (T2) on ≥28 days later. To determine HPA suppression, area under the effect curve over 28 days and maximum change from baseline were calculated for cortisol, glucose levels, and white blood cell (WBC) count. Equivalent effect on HPA suppression of T1 relative to T2 was determined if the 90% CIs for ratios of these measures were within 80%–125%. The effect of repeat injections on leg and back pain was also assessed.

Results

Based on the responder analysis, all subjects had achieved a cortisol response by day 3 after initial injection and by day 2 after repeat injection. The repeat injection had similar effects on glucose levels and WBC count to the initial injection. Pain scores decreased after each injection and remained low for the 28-day follow-up, with some evidence of improved analgesic effect of the second dose compared with the first. There were no serious adverse events or discontinuations due to adverse events.

Conclusion

The lack of cumulative effect and rapid resolution of HPA suppression following repeated SP-102 dosing suggests that consideration of HPA pharmacodynamics is not clinically relevant when making decisions regarding repeat dosing. SP-102 ESIs provided prolonged pain relief, with preliminary evidence of greater efficacy after repeat injection. A phase III trial is ongoing.

Clinical Trial Identifier

ClinicalTrials.gov: NCT03613662.

Impact of obstructive sleep apnea on cardiovascular risk in patients with acromegaly

OBJECTIVE

Respiratory complications represented by obstructive sleep apnea (OSA), cardiovascular disease (CVD), and metabolic disorders including insulin resistance (IR) are common in patients with acromegaly. OSA is further associated with a higher risk of IR and CVD in the general population. However, significant information on the effect of OSA on IR and CVD risk for patients with acromegaly remains to be scarce.

PATIENTS AND METHODS

This retrospective study included 125 patients with active acromegaly. Medical history, anthropometric parameters, polysomnographic and fasting biochemical measurements were collected. Ten-year Framingham CVD risk scores were calculated and categorized as low, moderate, and high. IR was assessed using the homeostasis model assessment (HOMA-IR).

RESULTS

OSA was confirmed in two thirds of the enrolled patients. Compared with patients without OSA, patients with both OSA and acromegaly were found to have higher proportion of HOMA-IR and moderate-to-high 10-year CVD risk. Logistic regression analysis showed that OSA, HOMA-IR, and low-density lipoprotein cholesterol were all risk factors for moderate-to-high CVD risk. Meanwhile, no mediating effect of HOMA-IR in the association between OSA and Framingham CVD risk was observed in patients with acromegaly.

CONCLUSIONS

The coexistence of OSA might increase the CVD risk for patients with acromegaly, and IR might independently contribute to CVD risk in acromegalic patients with OSA.

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.

d-allulose Ameliorates Metabolic Dysfunction in C57BL/KsJ-db/db Mice

d-allulose is an uncommon sugar that provides almost no calories when consumed. Its sweetness is 70% that of sucrose. d-allulose is a metabolic regulator of glucose and lipid metabolism. However, few reports concerning its effect on diabetes and related metabolic disturbances in db/db mice are available. In this study, we evaluated d-allulose's effect on hyperglycemia, hyperinsulinemia, diabetes and inflammatory responses in C57BL/KsJ-db/db mice. Mice were divided into normal diet, erythritol supplemented (5% w/w), and d-allulose supplemented (5% w/w) groups. Blood glucose and plasma glucagon levels and homeostatic model assessment (HOMA-IR) were significantly lower in the d-allulose group than in the normal diet group, and plasma insulin level was significantly increased. Further, d-allulose supplement significantly increased hepatic glucokinase activity and decreased hepatic phosphoenolpyruvate carboxykinase and glucose-6-phosphatase activity. Expression of glucose transporter 4, insulin receptor substrate 1, phosphatidylinositol-4,5-bisphosphate 3-kinase catalytic subunit alpha and AKT serine/threonine kinase 2 were also upregulated by d-allulose supplement in adipocyte and muscle. Finally, d-allulose effectively lowered plasma and hepatic triglyceride and free fatty acid levels, and simultaneously reduced hepatic fatty acid oxidation and carnitine palmitoyl transferase activity. These changes are likely attributable to suppression of hepatic fatty acid synthase and glucose-6-phosphate dehydrogenase activity. Notably, d-allulose also reduced pro-inflammatory adipokine and cytokine levels in plasma. Our results indicate that d-allulose is an effective sugar substitute for improving lipid and glucose metabolism.

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.

Mechanisms of putative IGF-I receptor resistance in active acromegaly

Acromegaly is a disease characterized by overproduction of growth hormone (GH). As a consequence of excessive GH secretion, circulating insulin-like growth factor-I (IGF-I) is elevated in active (untreated) acromegaly. IGF-I is often used as a marker of disease activity and growth hormone status in acromegaly. Although IGF-I can directly improve insulin sensitivity and glucose uptake in muscles, the excessive GH secretion in active acromegaly frequently leads to insulin resistance, glucose intolerance and even diabetes. In this review evidence will be discussed that in active acromegaly chronically elevated IGF-I, insulin and soluble Klotho (S-Klotho) levels play a pathophysiological role in the development of IGF-I receptor (IGF-IR) resistance. It is postulated that as soon as circulating IGF-I, insulin and S-Klotho rise above a certain level the IGF-IR becomes relatively resistant to actions of IGF-I. The development of a degree of IGF-IR resistance for metabolic actions may help to explain why in active acromegaly diabetogenic effects of GH predominate and are not completely counteracted and neutralized by elevated circulating levels of IGF-I. Further studies are necessary in order to support this hypothesis.

Resolution of Long-Standing Diabetes Mellitus Two Years After Surgery for Growth Hormone Producing Pituitary Tumor

Excess serum growth hormone (GH) induces insulin resistance leading to reduced uptake of glucose in peripheral tissues, gluconeogenesis in the liver and lipolysis and finally an increase in the blood glucose levels. We report a case where a 54-year-old woman presented with uncontrolled blood glucose levels since 5 years. On examination, she had signs and symptoms consistent with acromegaly including recurrent headaches, sleep apnea, soft tissue swelling, enlargements of the feet, hands, ears and lips, mandibular overgrowth, forehead protrusio and teeth spacing. She was on oral hypoglycemic agents (OHAs) for 12 years before she visited our hospital, but the blood glucose levels have been uncontrolled for the past 5 years with recurrent hyperglycaemic and occasional hypoglycaemic events. She underwent pituitary surgery for GH producing tumor and 2 years post surgery, we had to stop all the medications for the diabetes mellitus. This indicates that even long-standing diabetes mellitus can resolve in some patients with acromegaly.

Increased ATP synthesis might counteract hepatic lipid accumulation in acromegaly

Patients with active acromegaly (ACRO) exhibit low hepatocellular lipids (HCL), despite pronounced insulin resistance (IR). This contrasts the strong association of IR with nonalcoholic fatty liver disease in the general population. Since low HCL levels in ACRO might be caused by changes in oxidative substrate metabolism, we investigated mitochondrial activity and plasma metabolomics/lipidomics in active ACRO. Fifteen subjects with ACRO and seventeen healthy controls, matched for age, BMI, sex, and body composition, underwent 31P/1H-7-T MR spectroscopy of the liver and skeletal muscle as well as plasma metabolomic profiling and an oral glucose tolerance test. Subjects with ACRO showed significantly lower HCL levels, but the ATP synthesis rate was significantly increased compared with that in controls. Furthermore, a decreased ratio of unsaturated-to-saturated intrahepatocellular fatty acids was found in subjects with ACRO. Within assessed plasma lipids, lipidomics, and metabolomics, decreased carnitine species also indicated increased mitochondrial activity. We therefore concluded that excess of growth hormone (GH) in humans counteracts HCL accumulation by increased hepatic ATP synthesis. This was accompanied by a decreased ratio of unsaturated-to-saturated lipids in hepatocytes and by a metabolomic profile, reflecting the increase in mitochondrial activity. Thus, these findings help to better understanding of GH-regulated antisteatotic pathways and provide a better insight into potentially novel therapeutic targets for treating NAFLD.

Hypertension in Acromegaly in Relationship to Biochemical Control and Mortality: Global ACROSTUDY Outcomes

CONTEXT

Hypertension is a major cardiovascular risk factor related to increased mortality in acromegaly. Surgical cure of acromegaly is associated with improvement in blood pressure levels, however little is known about the effect of pegvisomant (PEGV) treatment in patients with hypertension. This analysis evaluates outcomes in patients with hypertension and acromegaly included in ACROSTUDY.

METHODS

ACROSTUDY is a global non-interventional surveillance study of long-term treatment with PEGV, monitoring its safety and efficacy. The cohort was retrospectively divided in two subgroups: patients with and without hypertension. Stepwise logistic regression and Kaplan-Meyer analyses were performed for testing predictors of mortality.

RESULTS

The total cohort included 2,090 patients with acromegaly treated with PEGV who were followed for a median of 6.8 years (range up to 12.1 years). In ACROSTUDY there were 1,344 patients with hypertension (52.3% males). This subgroup was older, had a higher BMI, and higher prevalence of diabetes, hyperlipidemia, and cardiovascular disease (CVD) when compared to patients without hypertension. During ACROSTUDY, 68 deaths were reported in the hypertension cohort, vs 10 in the cohort without hypertension. Both CVD (p<0.0001) and anterior pituitary deficiencies (p=0.0105) at study entry independently predicted mortality in patients with acromegaly and hypertension; Kaplan-Meier analysis confirmed that CVD significantly impairs survival.

CONCLUSIONS

Hypertension is common in patients with acromegaly and significantly increases mortality, especially when there is concomitant CVD. These data suggest that treatment goals should extend beyond IGF-I normalization, and include optimisation of substitution of pituitary deficiencies and scrutinous screening and treatment of CVD.

Determinants of morbidities and mortality in acromegaly

Acromegaly is a systemic disease associated with increased morbidity, presenting cardiovascular, metabolic, respiratory, neoplastic, endocrine, articular and bone complications. Most of these comorbidities can be prevented or delayed with adequate disease treatment and, more recent studies with the use of modern treatments of acromegaly, have shown a change in the severity and prevalence of these complications. In addition, acromegaly is associated with increased mortality, but recent studies (especially those published in the last decade) have shown a different scenario than older studies, with mortality no longer being increased in adequately controlled patients and a change in the main cause of death from cardiovascular disease to malignancy. In this review, we discuss this changing face of acromegaly summarizing current knowledge and evidence on morbimortality of the disease. Arch Endocrinol Metab. 2019;63(6):630-7.