The abnormalities of carbohydrate metabolism in Turner syndrome: analysis of risk factors associated with impaired glucose tolerance

Transition from pediatric to adult care in patients with Turner syndrome in Italy: a consensus statement by the TRAMITI project

PURPOSE

Transition from pediatric to adult care is associated with significant challenges in patients with Turner syndrome (TS). The objective of the TRansition Age Management In Turner syndrome in Italy (TRAMITI) project was to improve the care provided to patients with TS by harnessing the knowledge and expertise of various Italian centers through a Delphi-like consensus process.

METHODS

A panel of 15 physicians and 1 psychologist discussed 4 key domains: transition and referral, sexual and bone health and oncological risks, social and psychological aspects and systemic and metabolic disorders.

RESULTS

A total of 41 consensus statements were drafted. The transition from pediatric to adult care is a critical period for patients with TS, necessitating tailored approaches and early disclosure of the diagnosis to promote self-reliance and healthcare autonomy. Fertility preservation and bone health strategies are recommended to mitigate long-term complications, and psychiatric evaluations are recommended to address the increased prevalence of anxiety and depression. The consensus also addresses the heightened risk of metabolic, cardiovascular and autoimmune disorders in patients with TS; regular screenings and interventions are advised to manage these conditions effectively. In addition, cardiac abnormalities, including aortic dissections, require regular monitoring and early surgical intervention if certain criteria are met.

CONCLUSIONS

The TRAMITI consensus statement provides valuable insights and evidence-based recommendations to guide healthcare practitioners in delivering comprehensive and patient-centered care for patients with TS. By addressing the complex medical and psychosocial aspects of the condition, this consensus aims to enhance TS management and improve the overall well-being and long-term outcomes of these individuals.

Prevalence and Predictors of Prediabetes in Adolescents and Young Adults with Turner Syndrome: A Cross-Sectional Study from Eastern India

Background

Individuals with Turner syndrome (TS) have a high risk for prediabetes/type 2 Diabetes Mellitus (T2DM). There is scarce data regarding risk factors for prediabetes in TS, specially from South Asia.

Methods

We conducted a cross-sectional study on girls with TS aged 12-30 years who had achieved pubertal stage B3 and above-spontaneously or with oestrogen. Anthropometric measurements and biochemical tests were conducted, and medical records were reviewed for details about pubertal onset and progression, growth hormone (GH) and oestrogen therapy.

Results

Out of 129 patients with TS in our database, 99 met the criteria for inclusion, mean age 18.33+/-3.78 years and mean BMI 20.57+/- 3.71 kg/m2. Prevalence of prediabetes was 23.23%. Plasma-glucose measured after 75 g-oral-anhydrous-glucose-load (OGTT-PPG) identified five additional prediabetes cases, who had normal fasting plasma glucose (FPG) or HbA1c%. Compared to those without prediabetes, TS with prediabetes (n = 23) had higher mean body weight, BMI, waist circumference (WC) [42.02+/- 5.83 vs 36.22+/-8.07, 22.77+/-2.78 vs 19.91+/- 3.72, 85.26+/- 3.52 vs 81.08+/- 4.59, pall < 0.03 ], higher median WC-to-height ratio (WHtR) and WC-to-hip ratio (WHR)((0.64 [0.6-0.69] vs 0.59[0.56- 0.66], 0.9[0.84-1.12] vs 0.85[0.75-1.01], pboth < 0.02), and higher LDL-cholesterol, triglycerides, and greater prevalence of hepatosteatosis (47.1% vs 21.1%, P < 0.01). Among GH recipients (n = 36), those with prediabetes had delayed initiation and shorter duration of GH therapy. There were no differences in cardiometabolic parameters or the prevalence of diabetes between different karyotypic variants of TS. BMI, WC and WHR had significant positive correlation with FBG, OGTT-PPG and HbA1c% (pall < 0.004). Delay in oestrogen initiation had a significant correlation with OGTT-PPG (Spearman's-rho = 0.69, P < 0.004). BMI, WHR and pubertal status were independent predictors for prediabetes (OR: 1.27 [1.03-1.57]), 1.18 [1.04-1.34]) and 0.09[0.02-0.38], respectively, pall < 0.02), but karyotype was not. BMI had the highest sensitivity [cut-off: 21.04 kg/m2 (sensitivity: 82.6%, specificity: 62.2%) and WHR had the highest specificity [cut-off: 0.89 (sensitivity: 73.9%, specificity 78.4%)] for predicting prediabetes.

Conclusion

Indian girls with TS have a high risk for prediabetes, irrespective of underlying karyotype and should be screened with oral glucose challenge to identify prediabetes. Timely intervention against central obesity and early initiation of GH and oestrogen should be ensured in TS. Late presenting girls should be closely monitored for dysglycaemia before and during treatment with GH and/or oestrogen.

Hyperglycemia in Turner syndrome: Impact, mechanisms, and areas for future research

Turner syndrome (TS) is a common chromosomal disorder resulting from complete or partial absence of the second sex chromosome. Hyperglycemia, ranging from impaired glucose tolerance (IGT) to diabetes mellitus (DM), is common in TS. DM in individuals with TS is associated with an 11-fold excess in mortality. The reasons for the high prevalence of hyperglycemia in TS are not well understood even though this aspect of TS was initially reported almost 60 years ago. Karyotype, as a proxy for X chromosome (Xchr) gene dosage, has been associated with DM risk in TS - however, no specific Xchr genes or loci have been implicated in the TS hyperglycemia phenotype. The molecular genetic study of TS-related phenotypes is hampered by inability to design analyses based on familial segregation, as TS is a non-heritable genetic disorder. Mechanistic studies are confounded by a lack of adequate TS animal models, small and heterogenous study populations, and the use of medications that alter carbohydrate metabolism in the management of TS. This review summarizes and assesses existing data related to the physiological and genetic mechanisms hypothesized to underlie hyperglycemia in TS, concluding that insulin deficiency is an early defect intrinsic to TS that results in hyperglycemia. Diagnostic criteria and therapeutic options for treatment of hyperglycemia in TS are presented, while emphasizing the pitfalls and complexities of studying glucose metabolism and diagnosing hyperglycemia in the TS population.

Increased Prevalence of Beta-Cell Dysfunction despite Normal HbA1c in Youth and Young Adults with Turner Syndrome

INTRODUCTION

Adult women with Turner syndrome (TS) have a high prevalence of diabetes and β-cell dysfunction that increases morbidity and mortality, but it is unknown if there is β-cell dysfunction present in youth with TS. This study aimed to determine the prevalence of β-cell dysfunction in youth with TS and the impact of traditional therapies on insulin sensitivity (SI) and insulin secretion.

METHODS

Cross-sectional, observational study recruited 60 girls with TS and 60 healthy controls (HC) matched on pubertal status. Each subject had a history, physical exam, and oral glucose tolerance test (OGTT). Oral glucose and c-peptide minimal modeling was used to determine β-cell function.

RESULTS

Twenty-one TS girls (35%) met criteria for prediabetes. Impaired fasting glucose was present in 18% of girls with TS and 3% HC (p value = 0.02). Impaired glucose tolerance was present in 23% of TS girls and 0% HC (p value <0.001). The hemoglobin A1c was not different between TS and HC (median 5%, p = 0.42). Youth with TS had significant reductions in SI, β-cell responsivity (Φ), and disposition index (DI) compared to HC. These differences remained significant when controlling for body mass index z-score (p values: 0.0006, 0.002, <0.0001 for SI, Φ total, DI, respectively).

CONCLUSIONS

β-Cell dysfunction is present in youth with TS compared to controls. The presence of both reduced insulin secretion and SI suggest a unique TS-related glycemic phenotype. Based on the data from this study, we strongly suggest that providers employ serial OGTT to screen for glucose abnormalities in TS youth.

Insulin Sensitivity and Pancreatic β-Cell Function in Ecuadorian Women With Turner Syndrome

Objective: To assess insulin sensitivity and pancreatic β-cell function in an adult population of Ecuadorian individuals with Turner syndrome (TS). Design and Methods: This was a cross-sectional correlational study conducted in TS subjects (>20 years old; n = 38). A standard 2-h oral glucose tolerance test was performed in both women with TS and the reference group. Glucose, lipids, insulin, and C-peptide concentrations were measured. Homeostasis Model Assessment (HOMA) of Insulin Resistance, Quantitative Insulin Sensitivity Check Index, McAuley, Matsuda, and Belfiore indices were calculated to evaluate the degree of insulin resistance (IR). The pancreatic β-cell function was assessed using HOMA-β, basal C-Peptide Index (CPI), and CPII at 120'. Results: A higher prevalence of impaired glucose tolerance was found in TS subjects compared with the reference group. Although significant differences were found for glucose concentrations at 60' and 120' (but not at 0'), only the baseline insulin concentrations differed significantly between the two groups. The values of the IR indices were statistically different between study and reference groups. A significant number of TS subjects diagnosed with IR were differently classified according to the index applied. The concentrations of C-peptide at 0' and 120' of TS subjects were similar to those of the control group. In contrast, the CPI and CPII values in the study group were significantly lower than those in the control group. Conclusion: It is impossible to select the best surrogate method for the assessment of IR in women with TS. The CPI and CPII values could be preferable to other indices to assess the pancreatic β-cell function in TS subjects. Our findings suggest that IR and pancreatic β-cell dysfunction could be independent events in women with TS, and both conditions seem to be caused by the disease per se. Our results imply that early screening and intervention for TS would be therapeutic for TS women.

Recognition and management of adults with Turner syndrome: From the transition of adolescence through the senior years

Turner syndrome is recognized now as a syndrome familiar not only to pediatricians and pediatric specialists, medical geneticists, adult endocrinologists, and cardiologists, but also increasingly to primary care providers, internal medicine specialists, obstetricians, and reproductive medicine specialists. In addition, the care of women with Turner syndrome may involve social services, and various educational and neuropsychologic therapies. This article focuses on the recognition and management of Turner syndrome from adolescents in transition, through adulthood, and into another transition as older women. It can be viewed as an interpretation of recent international guidelines, complementary to those recommendations, and in some instances, an update. An attempt was made to provide an international perspective. Finally, the women and families who live with Turner syndrome and who inspired several sections, are themselves part of the broad readership that may benefit from this review.

Glucose Metabolism in Turner Syndrome

Turner syndrome (TS) is one of the most common female chromosomal disorders. The condition is caused by complete or partial loss of a single X chromosome. Adult patients with TS have a high prevalence of diabetes mellitus (DM). Deranged glucose metabolism in this population seems to be genetically triggered. The traditional risk factors for DM in the general population may not play a major role in the pathogenesis of DM in patients with TS. This review focuses on the latest research studies pertaining to abnormalities of glucose metabolism in TS. We extensively review the available evidence pertaining to the influence of insulin secretion and sensitivity, obesity, autoimmunity, lifestyle, growth hormone, and sex hormone replacement therapy on the occurrence of DM in these patients.

X-chromosome gene dosage and the risk of diabetes in Turner syndrome

BACKGROUND

Turner syndrome (TS) is caused by the absence or fragmentation of the second sex chromosome. An increased risk of diabetes mellitus (DM) has consistently been noted, but the specific phenotype and genetic etiology of this trait are unknown.

METHODS

In a prospective study, we examined the prevalence of DM in adult participants in an intramural National Institutes of Health (NIH) TS study. Results were analyzed with respect to karyotype, age, body mass index (BMI), and autoimmune indices. Insulin sensitivity and secretion were compared in age- and BMI-matched euglycemic women with TS and healthy female controls. We compared gene expression profiles in lymphocytes from differentially affected TS groups.

RESULTS

Type 2 DM was present in 56 of 224 (25%) of the women with TS; type 1 DM was found in only one woman (<0.5%). DM was more prevalent among women with an isoXq chromosome compared to X monosomy (40.0 vs. 17.3%; P = 0.004). Euglycemic women with TS (n = 72; age, 33 +/- 12 yr; BMI, 23 +/- 3 kg/m(2)) had significantly higher glycemic and lower insulin responses to OGTT, with insulin sensitivity similar to controls. Gene expression profiles comparing 46,X,i(X)q vs. 45,X groups showed a significant increase in Xq transcripts and in potentially diabetogenic autosomal transcripts in the isoXq group.

CONCLUSION

Type 2 DM associated with deficient insulin release is significantly increased among women with monosomy for the X-chromosome but is increased even more among women with monosomy for Xp coupled with trisomy for Xq. These data suggest that haploinsufficiency for unknown Xp genes increases risk for DM and that excess dosage of Xq genes compounds the risk.

Nailfold video capillaroscopy in Turner syndrome: a descriptive study

BACKGROUND: An increased prevalence of impaired glucose homeostasis is reported in Turner syndrome. Endothelial changes are described in patients with insulin resistance, which may be present in patients with Turner syndrome. Video capillaroscopy is a noninvasive examination that allows assessment of vascular patency. OBJECTIVE: To describe the nailfold morphology of capillaries in Turner syndrome using video capillaroscopy. METHODS: Subjects were studied in a temperature-controlled room, 20 days after no nailfold manipulations. The capillaries were visualized by microscope connected to a television and computer and were studied and classified according to these patterns: loop distribution, papilla, avascular fields, edema, form, capillary limbs, flow and hemorrhagic extravasation. RESULTS: Fifty patients aged between 6-37 years with Turner syndrome were studied. Eighteen (36%) patients had normal capillaroscopy with hairpin pattern in loop distribution and no avascular fields. The papilla was ratified in 13 (26%) and enlarged in four (8%). Edema occurred in 22 (44%) cases. There were three (6%) macrocapillaries and three (6%) were branched. Tortuosity was present in five (10%) patients. Hemorrhagic extravasation occurred in one (2%) case. Flow was fast in seven (14%), granulous in five (10%) and slow in six (12%). CONCLUSION: There was a high prevalence of nailfold capillaroscopy changes in Turner syndrome and the most prevalent alterations found were edema and ratified papilla.