Predictors of worsening insulin sensitivity in postmenopausal women

The influence of estro-progestin therapy on neurohormonal activity in functional hypothalamic amenorrhea

Background: Functional hypothalamic amenorrhea (FHA) is a chronic endocrine disorder caused by the abnormal pulsatile secretion of neurohormones in the hypothalamus. Secretion of GnRH is regulated by kisspeptin/neurokinin B/dynorphin (KNDy) neurons. These neurons produce, among other neurohormones, neurokinin B (NKB) which regulates the coordinated stimulation or inhibition of GnRH secreting neurons. Aim of the study: Assessment and comparison of serum NKB in patients with FHA at baseline, and following 6 months of estrogen-progestagen therapy. Materials and methods: Fifty-five patients with functional hypothalamic amenorrhea were included in the study group. Serum concentrations of neurokinin B (NKB), follicle stimulating hormone (FSH), luteinizing hormone (LH), 17-β-estradiol (E2), prolactin (PRL), cortisol, testosterone (T), dehydroepiandrosterone sulfate (DHEA-S), thyroid-stimulating hormone (TSH), free thyroxine (fT4), fasting glucose and insulin, as well as lipid profile were measured at baseline. At the time of diagnosis, patients with FHA were prescribed a course of 2 mg 17-β-estradiol and 10 mg dydrogesterone for duration of 6 months. Serum NKB was then reassessed following treatment at 6 months. Results: At baseline, the FHA group was found to have a decreased serum NKB concentration when compared to a healthy control group. Following 6 months of sequential estrogen-progestogen hormone therapy, this study did not find any statistically significant difference in serum NKB concentration in the treatment arm compared to baseline. Conclusions: For the first time, NKB secretion has been studied in patients with FHA. A significantly lower level of serum NKB was observed in these patients at baseline, when compared to a control group. After 6 months of combination estrogen-progesterone therapy, no significant changes in NKB levels were observed in these patients. These findings, for the first time in the literature, provide insight into the perceived benefit of HRT, calling into question its benefit in addressing the underlying etiopathogenetic contributors of FHA. These new findings may contribute to more targeted and appropriate treatment of such patients in the future.

Associations of polychlorinated biphenyl exposure and endogenous hormones with diabetes in post-menopausal women previously employed at a capacitor manufacturing plant

There is an increasing body of literature showing associations of organochlorine exposure with risk of diabetes and insulin resistance. Some studies suggest that associations differ by gender and that diabetes risk, in turn, may be affected by endogenous steroid hormones. This report examines the relationships of serum PCBs and endogenous hormones with history of diabetes in a cohort of persons previously employed at a capacitor manufacturing plant. A total of 118 women were post-menopausal with complete data, of whom 93 were not using steroid hormones in 1996, at the time of examination, which included a survey of exposure and medical history, height, weight and collection of blood and urine for measurements of lipids, liver function, hematologic markers and endogenous hormones. This analysis examines relationships of serum polychlorinated biphenyls (PCBs), work exposure and endogenous hormones with self-reported history of diabetes after control for potential confounders. All PCB exposure groups were significantly related to history of diabetes, but not to insulin resistance as measured by the homeostatic model assessment of insulin resistance (HOMA-IR) in non-diabetics. Diabetes was also independently and inversely associated with follicle stimulating hormone (FSH), dehydroepiandrosterone sulfate (DHEAS) and triiodothyronine (T3) uptake. HOMA-IR was positively associated with body mass index (BMI) and C-reactive protein (CRP) and inversely associated with sex hormone binding globulin (SHBG) and T3 uptake after control for PCB exposure. Possible biologic mechanisms are discussed. This study confirms previous reports relating PCB exposure to diabetes and suggests possible hormonal pathways deserving further exploration.

Risk factors of type 2 diabetes among Korean adults: The 2001 Korean national health and nutrition examination survey

This study aimed to identify risk factors for type 2 diabetes (T2D) in Korea, a rapidly changing country. Data of 5,132 adults aged 20-85 were used from the 2001 Korean Health and Nutrition Examination Survey. Multiple logistic regression was carried out to identify risk factors for T2D. Three models were specified: (i) socioeconomic and demographic factors (model 1: age, gender, education, poverty income ratio, employment), (ii) behavioral risk factors and covariates (model 2: obesity, physical activity, smoking, alcohol drinking, dietary quality, family history of T2D, co-morbidity) and (iii) socioeconomic, demographic, and behavioral factors (model 3). The prevalence of T2D was 7.4%. Less education (OR 1.41, 95% CI 1.08-1.84), age (OR 2.19, 95% CI 1.56-3.08 in 40-59 yrs, OR 4.05, 95% CI 2.76-5.95 in 60 yrs + comparing to 20-39 yrs) and abdominal obesity (OR 2.24, 95% CI 1.79-2.82) were risk factors for T2D even after controlling for other factors simultaneously. There was a significant association of T2D with ever smoking (OR 1.34, 95% CI 1.06-1.67). The relationship of age with T2D was modified by gender in model 1 and the relationship of smoking with T2D was modified by obesity in model 2. Less educated, older, obese or ever smokers were more likely to have T2D. Gender mediated the relationship of age, and obesity mediated the relationship of smoking, with T2D. Intervention programs for T2D in Korea should take the interactions among risk factors into account.

Differential effects of various progestogens on metabolic risk factors for breast cancer

Biological and epidemiological findings suggest that metabolic factors - insulin, insulin-like growth factor-I (IGF-I) and sex hormone-binding globulin (SHBG) - are involved in the development and promotion of breast cancer. Estrogens, particularly if administered orally, counteract metabolic factors that increase breast cancer risk, i.e. they reduce insulin and IGF-I and increase SHBG. This could contribute toward explaining epidemiological data showing that unopposed oral estrogens do not increase breast cancer risk, or do so only modestly. In contrast to natural progesterone and progesterone-derived progestins, progestins endowed with androgenic (or glucocorticoid) activity negatively influence these metabolic factors, counteracting the favorable effects of estrogens. While most biological and epidemiological findings suggest that natural progesterone does not augment breast cancer risk, available data show an increased risk with synthetic progestins - with the possible exception of progesterone-derived dydrogesterone. Different mechanisms for different progestins could possibly be involved. Differences from progesterone with regard to pharmacokinetics and pharmacodynamics, potency, interaction with the two isoforms of the progesterone receptor, and binding to other steroid receptors could all be relevant. These remain theoretical speculations for the time being, but the possibility that some progestins increase breast cancer risk through their negative influence on metabolic factors cannot be rejected.

Insulin resistance with hormone replacement therapy: associations with markers of inflammation and adiposity

OBJECTIVE

This study was undertaken to determine whether insulin resistance associated with combination hormone replacement therapy (HRT) is mediated by changes in serum markers of inflammation or in serum adipocyte hormones.

STUDY DESIGN

Forty-five postmenopausal women, aged 55 +/- 7 years, were examined from a randomized, double-blind placebo-controlled trial evaluating the effect of HRT on insulin-stimulated glucose disposal and body composition. Volunteers were randomly assigned to conjugated estrogens 0.625 mg plus medroxyprogesterone acetate 2.5 mg vs placebo for 1 year. At baseline and at 1 year, body composition was assessed by dual photon x-ray absorptiometry scans; body fat distribution was measured by computed tomographic scans at the L4/L5 vertebral disk space; insulin sensitivity was measured by euglycemic hyperinsulinemic clamp; interleukin-6 (IL-6), leptin, and adiponectin were measured by enzyme-linked immunosorbent assay; and c-reactive protein (CRP) was measured by radioimmunoassay.

RESULTS

HRT increased CRP by 121% compared with a 32% increase with placebo (P = .03); HRT decreased glucose disposal by 17% compared with no change with placebo (P = .04) as reported previously. HRT did not affect body composition, body fat distribution, IL-6, leptin, or adiponectin. The increase in CRP did not correlate with the decrease in glucose disposal in the HRT group (R = 0.11, P = .65).

CONCLUSION

Treatment with HRT for one year increases CRP, but does not alter IL-6, adiponectin, or leptin. The change in CRP was not, however, related to the decrease in glucose disposal with HRT treatment.