Blunted cerebral oxygenation during exercise in women with gestational diabetes mellitus: associations with macrovascular function and cardiovascular risk factors.

AIM/HYPOTHESIS: This cross-sectional, observational, controlled study examined cerebral oxygenation during exercise, an index of cerebrovascular function and cortical activation, in pregnancies complicated by gestational diabetes mellitus (GDM) and unaffected pregnancies. The association of cerebral oxygenation with macrovascular and cardiovascular function indices was also evaluated. MATERIAL AND METHODS: Vascular function and structure [aortic pulse-wave-velocity (PWV), augmentation index (AI), carotid intima-media thickness], as well as 24-hour ambulatory blood pressure (BP) were assessed in women with GDM (n = 21) and uncomplicated pregnancies (n = 16), at 26-32 gestational weeks. Changes in cerebral oxygenation [oxy- (O2Hb), deoxy- (HHb) and total- (tHb) hemoglobin] were continuously recorded by near-infrared spectroscopy (NIRS) during intermittent handgrip exercise. Beat-by-beat BP and systemic vascular resistance (SVR) were assessed (Finapres). RESULTS: Women with GDM had higher AI than controls. During exercise, women with GDM maintained a smaller force (p < 0.05), despite similar ratings of perceived exertion. Despite similar increases in BP during exercise, the GDM group exhibited a lower average and total (AUC) increase in cerebral-O2Hb than controls (p < 0.05). In addition, GDM exhibited a slower rate of cerebral-O2Hb decay during recovery (p < 0.05). SVR was lower in GDM compared to controls throughout the protocol (p < 0.01). Cerebral oxygenation indices were correlated with PWV and AI (p < 0.05). CONCLUSIONS: This study provided novel evidence for blunted cerebral oxygenation during exercise in women with GDM compared to uncomplicated pregnancies, suggesting a link between reduced cerebrovascular function with exercise intolerance in GDM. Cerebral oxygenation during physical stress was correlated with macrovascular function and cardiovascular risk factors. More studies are needed to examine whether this impaired cerebral oxygenation reflects early cerebrovascular disease.

Regulation of basal metabolic rate in uncomplicated pregnancy and in gestational diabetes mellitus.

Basal metabolic rate (BMR) is one of the major components of total energy expenditure (TEE). It is affected by various factors, such as body weight, body composition, age, race/ethnicity, gender, biochemical parameters, physical activity, and health status. Gestational diabetes mellitus (GDM) is the most common metabolic disorder during pregnancy and it increases the risk for health complications, such as stillbirth, diabetes mellitus, and cardiovascular disease in later life. Both BMR and GDM have been linked with gestational weight gain (GWG), a fact suggesting a possible association between them. However, assessing BMR is a complex procedure, which becomes more complicated when additional parameters, such as pregnancy and GDM, are taken into consideration. The present review summarizes the current knowledge on factors affecting BMR and its regulation in relation to pregnancy and GDM. Future research addressing these associations should thoroughly consider other factors that affect BMI when designing such studies and/or discussing the BMR outcome results.

Hypogonadism and non-alcoholic fatty liver disease.

Non-alcoholic fatty liver disease (NAFLD) is more common in men than in women. Thus, it has been suggested that sex steroids do have a role in the development of NAFLD. The aim of the current paper is to illustrate the association between NAFLD and hypogonadism, by reviewing data derived from both human and animal studies. The prevalence of NAFLD is high in men with hypogonadism, including those with idiopathic hypogonadotropic hypogonadism (IHH), as well as in women in post-menopause, those under estrogen receptor antagonist treatment or women with Turner syndrome. Estrogens seem to play a pivotal role in hepatic lipid homeostasis, as demonstrated in animal models with diminished ovarian estrogens (i.e., ovariectomized mice) and low serum testosterone (T) concentration is independently associated with NAFLD. The elucidation of the exact role of sex steroids in NAFLD pathogenesis would create a unique opportunity to develop novel therapies to tackle NAFLD disease.

Comments on gestational diabetes mellitus: from pathophysiology to clinical practice.

Gestational diabetes mellitus (GDM) is a topic of major interest, as it affects up to 16% of pregnant women and may lead to adverse pregnancy outcomes, which, however, are preventable by appropriate treatment. The aim of the present study was to discuss basic concepts and to critically appraise recent updates on practical issues in the field of GDM. GDM pathophysiology, long-term complications including "fetal programming" and GDM diagnosis are discussed, while clinical practice guidelines on follow-up, medical nutrition therapy, oral hypoglycemic agents and insulin treatment are also reviewed. GDM comprises a serious yet preventable public health problem and prevention by lifestyle changes, early detection and adequate treatment can lead to better health outcomes for both mothers with GDM and their offspring.

Prediction of maternal and neonatal adverse outcomes in pregnant women treated for hypothyroidism.

OBJECTIVE: To examine whether the concentrations of maternal serum TSH and free thyroxine (fT4) through pregnancy, the presence of thyroid autoimmunity (TAI) or the dose of levo-thyroxine (LT4) replacement can predict the occurrence of maternal or fetal/neonatal complications in pregnant women treated for maternal hypothyroidism. DESIGN: The study included 92 women with singleton pregnancies and primary hypothyroidism on LT4 replacement. Maternal serum TSH, fT4, thyroid auto-antibodies and doses of LT4 were monitored throughout pregnancy. All maternal and fetal/neonatal complications were recorded. RESULTS: The overall prevalence of maternal and neonatal complications was 24.1%. Neither maternal TSH/fT4 concentrations, presence of TAI nor dose of LT4 could predict the occurrence of complications. Pre-pregnancy body mass index (BMI) was higher in women who developed maternal complications [odds ratio (OR) 1.3, 95% confidence interval (CI) 1.1-1.5, p=0.007) and gestational week at delivery was lower in pregnancies complicated by neonatal (OR 0.5, 95% CI 0.3-0.8, p=0.001) or any type of complications (OR 0.6, 95% CI 0.4-0.9, p=0.008). CONCLUSIONS: The occurrence of maternal or fetal/neonatal complications in pregnant women treated for hypothyroidism cannot be predicted by maternal TSH/fT4 through pregnancy, presence of TAI or dose of LT4 replacement.

Serum thyrotropin concentration as a biochemical predictor of thyroid malignancy in patients presenting with thyroid nodules.

PURPOSE: Serum thyrotropin (TSH) is a well-established growth factor for thyroid nodules and suppression of TSH concentrations by administering exogenous thyroxine may interfere with the growth of established nodules as well as the formation of new thyroid nodules. The aim of this study was to investigate whether serum TSH at presentation is a predictor of thyroid malignancy in patients with thyroid nodules. METHODS: A total of 565 patients without overt thyroid dysfunction, who presented with palpable thyroid nodule(s) between 1988 and 2004 and underwent at least one fine-needle aspiration biopsy, were retrospectively evaluated. RESULTS: The final diagnostic outcome was established after surgery (n = 122) or after a minimum of 1-year clinical follow-up period. Higher rates of malignancy were observed in patients with serum TSH in the upper tertile of the normal range (P = 0.026). Binary logistic regression analysis revealed significantly increased adjusted odds ratios for the diagnosis of malignancy in patients with serum TSH 1.5-4.0 mIU/l when compared to those with either TSH 0.4-0.8 mIU/l (P = 0.005) or TSH 0.9-1.4 mIU/l (P = 0.007). CONCLUSIONS: The risk of malignancy in thyroid nodules increases in parallel with TSH concentrations within the normal range. TSH concentration at presentation is an independent predictor of thyroid malignancy.