Secondary diabetes mellitus in acromegaly

Management of Diabetes Mellitus in Acromegaly and Cushing's Disease with Focus on Pasireotide Therapy: A Narrative Review

Patients suffering from acromegaly and Cushing's Disease (CD) face the risk of several clinical complications. The onset of diabetes mellitus (DM) is among the most important: exposure to elevated growth hormone or cortisol levels is associated with insulin resistance (IR). DM contributes to increasing cardiovascular risk for these subjects, which is higher compared to healthy individuals. Hyperglycemia may also be caused by pasireotide, a second-generation somatostatin receptor ligand (SRLs), currently used for the treatment of these diseases. Accordingly, with 2014 medical expert recommendations, the management of hyperglycemia in patients with CD and treated with pasireotide is based on lifestyle changes, metformin, DPP-4 inhibitors (DPP-4i) and, subsequently, GLP-1 Receptor Agonists (GLP-1 RAs). There is no position for SGLT2-inhibitors (SGLT2-i). However, a very recent experts' consensus regarding the management of pasireotide-induced hyperglycemia in patients with acromegaly suggests the use of GLP-1 RAs as first line treatment (in suitable patients) and the use of SGLT2-i as second line treatment in patients with high cardiovascular risk or renal disease. As a matter of fact, beyond the hypoglycemic effect of GLP1-RAs and SGLT2-i, there is increasing evidence regarding their role in the reduction of cardiovascular risk, commonly very high in acromegaly and CD and often tough to improve despite biochemical remission. So, an increasing use of GLP1-RAs and SGLT2-i to control hyperglycemia is desirable in these diseases. Obviously, all of that must be done with due attention in order to minimize the occurrence of adverse events. For this reason, large studies are needed to analyze the presence of potential limitations.

A review of complex hormone regulation in thyroid cancer: novel insights beyond the hypothalamus-pituitary-thyroid axis

Like the ovaries and prostate, the thyroid exhibits characteristic hormone secretion and regulation. Thyroid cancer (TC), especially differentiated thyroid carcinoma, has typical sex-specific and age-specific hormone-driven clinical features. Previous research has primarily focused on the effects of thyroid stimulating hormone, thyroid hormones, and estrogens on the onset and progression of TC, while the roles of growth hormone (GH), androgens, and glucocorticoids have largely been overlooked. Similarly, few studies have investigated the interactions between hormones and hormone systems. In fact, numerous studies of patients with acromegaly have shown that serum levels of GH and insulin-like growth factor-1 (IGF-1) may be associated with the onset and progression of TC, although the influences of age, sex, and other risk factors, such as obesity and stress, remain unclear. Sex hormones, the GH/IGF axis, and glucocorticoids are likely involved in the onset and progression of TC by regulating the tumor microenvironment and metabolism. The aim of this review was to clarify the roles of hormones and hormone systems in TC, especially papillary thyroid carcinoma, as references for further investigations.

A Review on Coexisting Giants: The Interplay Between Acromegaly and Diabetes Mellitus

Acromegaly is a rare disease caused mainly by pituitary adenoma, which results in elevated growth hormone (GH) levels and its primary mediator, insulin-like growth factor (IGF-1). The condition causes various complications, including cardiovascular, respiratory, neuropsychiatric, metabolic, and gastrointestinal complications, which affect the patient's quality of life. Metabolically, there has been an increased incidence of acromegaly-associated diabetes mellitus (DM), IGF-1 being the primary mediator, affecting the patient's overall morbidity/mortality and associated surge in cardiovascular events. In the current state of medicine, both nonpharmacologic and pharmacologic approaches in managing acromegaly-associated DM are validated, having their own individualistic positive or negative impact on glucose metabolism. This review article has compiled studies to demonstrate a link between acromegaly. It summarises the existing data on acromegaly associated with DM, explicitly understanding the effect of various medical treatments on glucose homeostasis.

Effect of Cabergoline on weight and glucose metabolism in patients with acromegaly

PURPOSE

Cabergoline (CAB) has shown to have benefic effects on the metabolism in different clinical settings but its metabolic role in acromegaly disease has not been studied yet. Aim of our study was to evaluate the impact of CAB on glucose metabolism and weight in patients with acromegaly.

METHODS

All patients with acromegaly undergoing continuous treatment with CAB for at least 6 months were retrospectively screened. Exclusion criteria were discontinuation of CAB for more than one month, change of antidiabetic or other therapy for acromegaly, concomitant untreated hormonal deficiency, initiation of pregnancy and/or breastfeeding. All patients were evaluated in terms of biochemical disease control, glucose metabolism and weight at baseline (T0) and after the introduction of CAB therapy at 6 (T6) and 12 months (T12).

RESULTS

Twenty-six patients (15 females and 11 males) were evaluated at T0 and T6 and 19 patients (12 females and 7 males) were also evaluated at T12. Insulin-like growth factor I (IGF-I) and prolactin (PRL) levels were significantly lower at T6 and T12 compared to baseline (p < 0.001 for IGF-I, p < 0.05 for PRL) even if no further differences were observed between T12 and T6. Considering the entire cohort, no differences were appreciated regarding the metabolic parameters but a significant reduction in weight and body mass index (BMI) was observed at both T6 (p = 0.009 for weight, p = 0.021 for BMI) and T12 (p = 0.014 for weight, p = 0.017 for BMI) compared to baseline.

CONCLUSION

Our results confirm the efficacy of CAB in providing a significant improvement in the biochemical disease control but do not demonstrate a marked benefit on glucose metabolism of acromegaly patients. In such patients, CAB appears to have a rapid effect on weight and BMI, with significant changes noticeable as early as 6 months and persisting for at least 12 months.

Early Predictors of Remission in Acromegaly Patients after Pure Endoscopic Endonasal Transsphenoidal Surgery

Objective Surgery is the first-line treatment in acromegaly but it takes months to confirm remission. It is crucial to determine remission early in order to inform the patient and plan further treatment options. We aimed to evaluate the predictors of remission at the early phase after endoscopic endonasal pituitary surgery in acromegaly patients.

Methods Fifty-four growth hormone (GH)-adenoma patients operated via pure endoscopic endonasal approach were analyzed in this observational study. We compared the basic clinical, radiological characteristics, and the preoperative and postoperative hormone levels in terms of remission according to current guidelines.

Results The surgical remission rate was 61.1%. When the patients were compared according to surgical remission, the age, gender, and immunohistochemical granulation type were found to be nonsignificant, while diabetes mellitus was more common (55.6 vs. 44.4%). The preoperative tumor volume (1.2 ± 0.9 vs. 4.1 ± 4.2 cm3) and postoperative GH and insulin-like growth factor-1 (IGF-1) levels were higher in the nonremission group (p < 0.05). We defined a number of cut-off values of both GH and IGF-1 levels to predict remission at the postoperative phase. Age standardized regression analyses showed that postoperative day 1 (POD-1) GH levels (odds ratio [OR]: 8.9; 95% confidence interval [CI]: 1.99–40.0, p = 0.004) and tumor volume (OR: 3.14; 95% CI: 1.09–9.0, p = 0.034) were found to be significant independent predictors for remission.

Conclusion We demonstrated that tumor volume and POD-1 GH levels are independent predictors of remission in acromegaly patients operated via the pure endoscopic endonasal technique and may be used as an early marker of remission, and this may lead to taking adjuvant medical therapies early into account to improve prognosis.

Glucose intolerance in acromegaly is driven by low insulin secretion; results from an intravenous glucose tolerance test

PURPOSE

Insulin sensitivity (Si) and its role in glucose intolerance of acromegaly has been extensively evaluated. However, data on insulin secretion is limited. We aimed to assess stimulated insulin secretion using an intravenous glucose tolerance test (IVGTT) in active acromegaly.

METHODS

We performed an IVGTT in 25 patients with active acromegaly (13 normal glucose tolerance [NGT], 6 impaired glucose tolerance [IGT] and 6 diabetes mellitus [DM]) and 23 controls (8 lean NGT, 8 obese NGT and 7 obese IGT). Serum glucose and insulin were measured at 20 time points along the test to calculate Si and acute insulin response (AIRg). Medical treatment for acromegaly or diabetes was not allowed.

RESULTS

In acromegaly, patients with NGT had significantly (p for trend < 0.001) higher AIRg (3383 ± 1082 pmol*min/L) than IGT (1215 ± 1069) and DM (506 ± 600). AIRg was higher in NGT (4764 ± 1180 pmol*min/L) and IGT (3183 ± 3261) controls with obesity than NGT (p = 0.01) or IGT (p = 0.17) acromegaly. Si was not significantly lower in IGT (0.68 [0.37, 0.88] 106*L/pmol*min) and DM (0.60 [0.42, 0.84]) than in NGT (0.81 [0.58, 1.55]) patients with acromegaly. NGT (0.33 [0.30, 0.47] 106*L/pmol*min) and IGT (0.37 [0.21, 0.66]) controls with obesity had lower Si than NGT (p = 0.001) and IGT (p = 0.43) acromegaly.

CONCLUSION

We demonstrated that low insulin secretion is the main driver behind glucose intolerance in acromegaly. Compared to NGT and IGT controls with obesity, patients with NGT or IGT acromegaly had higher Si. Together, these findings suggest that impaired insulin secretion might be a specific mechanism for glucose intolerance in acromegaly.

A Case of Acromegaly With Progressed Diabetic Retinopathy and Sarcopenia Diagnosed Following the Onset of Severe Hypoglycemia

Acromegaly is a rare disorder characterized by excessive production of growth hormone (GH) from a pituitary tumor, typically leading to elevated glucose levels due to increased insulin resistance; hypoglycemia is rare. However, the long-term effect of excess GH on the peripheral organs is still unclear. Here we present a 69-year-old man evaluated for the cause of a hypoglycemic episode. He was underweight (body mass index: 17.3 kg/m2) with sarcopenia, which potentially contributed to his hypoglycemia. Notably, he exhibited progressed proliferative diabetic retinopathy compared to other microvascular complications, leading to further endocrinological investigation. As a result, he was diagnosed with acromegaly showing elevated GH and insulin-like growth factor-1 (IGF-1) with a pituitary tumor. Opting against transsphenoidal surgery (TSS), the patient was treated with a somatostatin analog (SSA), achieving normalized IGF-1 levels with a monthly 120 mg lanreotide injection. In this case, acromegaly could lead to sarcopenia from GH-derived gluconeogenesis in the peripheral organs such as the reduction of muscle leading to reduced glucose reserves. Acromegaly in the elderly may present atypicality. Clinicians should be vigilant for unique manifestations such as advanced diabetic retinopathy, even in elderly patients with hypoglycemia.

Secondary diabetes mellitus in pheochromocytomas and paragangliomas

Secondary diabetes mellitus (DM) in secretory pheochromocytomas and paragangliomas (PPGLs) is encountered in up to 50% of cases, with its presentation ranging from mild, insulin resistant forms to profound insulin deficiency states, such as diabetic ketoacidosis and hyperglycemic hyperosmolar state. PPGLs represent hypermetabolic states, in which adrenaline and noradrenaline induce insulin resistance in target tissues characterized by aerobic glycolysis, excessive lipolysis, altered adipokine expression, subclinical inflammation, as well as enhanced gluconeogenesis and glucogenolysis. These effects are mediated both directly, upon adrenergic receptor stimulation, and indirectly, via increased glucagon secretion. Impaired insulin secretion is the principal pathogenetic mechanism of secondary DM in this setting; yet, this is relevant for tumors with adrenergic phenotype, arising from direct inhibitory actions in beta pancreatic cells and incretin effect impairment. In contrast, insulin secretion might be enhanced in tumors with noradrenergic phenotype. This dimorphic effect might correspond to two distinct glycemic phenotypes, with predominant insulin resistance and insulin deficiency respectively. Secondary DM improves substantially post-surgery, with up to 80% remission rate. The fact that surgical treatment of PPGLs restores insulin sensitivity and secretion at greater extent compared to alpha and beta blockade, implies the existence of further, non-adrenergic mechanisms, possibly involving other hormonal co-secretion by these tumors. DM management in PPGLs is scarcely studied. The efficacy and safety of newer anti-diabetic medications, such as glucagon-like peptide 1 receptor agonists and sodium glucose cotransporter 2 inhibitors (SGLT2is), as well as potential disease-modifying roles of metformin and SGLT2is warrant further investigation in future studies.

FTO Gene Polymorphisms and Their Roles in Acromegaly

The major causes of both morbidity and mortality in patients with acromegaly are cardiovascular diseases (CVDs). The polymorphisms of the fat mass and obesity-associated gene (FTO) are associated with obesity, as well as with an increased risk of CVDs. The aim of the study was to determine the relationship of risk alleles of four FTO gene polymorphisms with selected parameters of lipid and glucose metabolism as well as with IGF-1 and GH levels in the group of patients with acromegaly compared to the control group. The study group consisted of 104 patients with acromegaly and 64 healthy subjects constituting the control group. In the whole acromegaly group, the data reveal that the homozygous for risk allele carriers (rs1421085, rs9930506, rs9939609) as well as carriers of only one risk allele have lower IGF-1 concentrations. In the well-controlled acromegaly group, the homozygous for three risk allele carriers of FTO gene polymorphisms have lower HDL cholesterol concentration (rs1121980, rs1421085, rs993609). In the cured acromegaly group, homozygous risk allele carriers rs9930506 tend to have higher levels of total cholesterol and LDL cholesterol. These associations are not observed in the control group. Conclusion: there is an association between FTO gene polymorphisms and the metabolism of lipids, suggesting that the FTO gene may be associated with higher CVD risk in patients with acromegaly. In addition, there is an association between FTO gene polymorphisms and IGF-1, implying that FTO gene may influence/modify IGF-1 synthesis. Further investigation on a larger scale is required to provide more precise evidence.