The phenomenon of regression-toward-the-mean

The Impact of Metformin on Plasma Prolactin Levels in Antipsychotics-Treated Men With Hyperprolactinemia and Early-Onset Androgenic Alopecia

OBJECTIVE

Metformin decreases elevated levels of pituitary hormones. Little is known about the association between the reproductive axis and hormonal effects of this drug. The purpose of our study was to investigate whether activity of the hypothalamic-pituitary-gonadal axis determines metformin action on prolactin levels in men with prolactin excess.

DESIGN/SUBJECTS/MEASUREMENTS

This prospective cohort study included two groups of men with drug-induced hyperprolactinemia and type 2 diabetes or prediabetes: men with normal hair growth (group A, n = 23) and men with late-onset androgenic alopecia (group B; n = 22). Both groups, matched for age, HOMA-IR, and prolactin concentration, were treated for 6 months with metformin. The outcomes of interest included glucose homeostasis markers (fasting glucose, glycated hemoglobin and HOMA-IR), plasma prolactin (both total and monomeric), other pituitary hormones (gonadotropins, TSH and ACTH), and peripheral hormones (testosterone, DHEAS and IGF-1).

RESULTS

Before metformin treatment, group B was characterized by higher values of LH, LH/FSH ratio, testosterone (total, free and bioavailable) and DHEAS compared to group A. Six-month metformin treatment reduced fasting glucose, glycated hemoglobin and HOMA-IR in both groups, though this effect was more pronounced in group A. The decrease in total and monomeric prolactin was observed only in group A. Their degree correlated inversely with total, free and bioavailable testosterone, positively with baseline prolactin levels, and positively with the impact on HOMA-IR. Compared to baseline values, follow-up LH was higher in group A and lower in group B.

CONCLUSIONS

These findings suggest that androgen excess may attenuate metformin action on overactive lactotrophs in men with early-onset androgenic alopecia.

Subclinical Hyperthyroidism Enhances Gonadotropin-Lowering Effects of Metformin in Postmenopausal Women

Metformin treatment decreases elevated concentrations of anterior pituitary hormones. The aim of this prospective, cohort study was to investigate whether hyperthyroidism modulates the impact of metformin on gonadotroph secretory function. The study population included 48 postmenopausal women with untreated type 2 diabetes or prediabetes, 24 of whom had coexisting grade 1 subclinical hyperthyroidism. Both groups were matched for age, insulin sensitivity, and gonadotropin levels. Over the entire study period, all participants were treated with metformin (2.55-3 g daily). Plasma glucose, insulin, thyroid-stimulating hormone (TSH), total and free thyroid hormones, follicle-stimulating hormone (FSH), luteinizing hormone (LH), estradiol, prolactin, adrenocorticotropic hormone (ACTH), and insulin-like growth factor-1 (IGF-1) were assayed at entry and 6 months later. At baseline, the study groups differed in levels of TSH and thyroid hormones but not in body mass index, blood pressure, glucose homeostasis markers (fasting glucose, homeostatic model assessment 1 of insulin resistance ratio [HOMA1-IR], and glycated hemoglobin [HbA1c]), and the remaining hormones. There were no differences between both groups in the degree of reduction in plasma glucose and HbA1c in response to metformin treatment. Although metformin decreased HOMA1-IR in both groups, this effect was stronger in women with hyperthyroidism than with normal thyroid function (-50 ± 20% vs -30 ± 15%). Similar relationships were observed for FSH (-43 ± 21% vs -21 ± 12%). Only in hyperthyroid women did the drug reduce LH concentration (by 35 ± 17%). Metformin did not affect circulating levels of TSH, total and free thyroxine, total and free triiodothyronine, estradiol, prolactin, ACTH, and IGF-1. The obtained results indicate that hyperthyroidism enhances the gonadotropin-lowering effects of metformin, as well as the fact that this agent has a neutral effect on the hypothalamic-pituitary-thyroid axis in case of its overactivity.

The Impact of Maternal Gestational Diabetes Mellitus on Minipuberty in Boys

BACKGROUND/OBJECTIVES

Minipuberty is thought to play an important role in the sexual maturation of infants. Maternal disorders during pregnancy were found to have an impact on the activity of the reproductive axis in the first year of life. This prospective, matched, cohort study was aimed at investigating whether the course of minipuberty in boys is affected by maternal gestational diabetes mellitus (GDM).

METHODS

The study population consisted of three matched groups of boys: infants born to women with poorly controlled GDM, sons of women with adequately controlled GDM, and infants of healthy women with normal carbohydrate tolerance during pregnancy (control group). Salivary levels of testosterone, androstenedione, DHEA-S and estradiol, and urinary concentrations of FSH and LH were repeatedly measured over the first 12 months of life. Hormone levels were correlated with the size of genital organs (testicular volume and penile length), which were measured at each visit.

RESULTS

Compared with the remaining groups, the male offspring of women with poorly controlled GDM were characterized by higher concentrations of both gonadotropins, higher salivary testosterone levels, lower salivary DHEA-S concentrations, and longer periods of detection for LH and testosterone. Levels of gonadotropin, testosterone and DHEA-S in sons of mothers with poorly controlled GDM correlated with mean levels of glycated hemoglobin during pregnancy. Moreover, the infant boys assigned to this group were characterized by larger sizes of the testes and penis. Over the entire study period, there were no differences in hormone levels, testicular volume and penile length between sons of adequately treated women with GDM and sons of healthy women.

CONCLUSIONS

The obtained results indicate that GDM, if poorly controlled, may affect the activity of the reproductive axis and postnatal growth of male genital organs in the offspring.

Impact of Lisinopril on Cardiometabolic Risk Factors in Sisters of Women With Polycystic Ovary Syndrome

Women with polycystic ovary syndrome (PCOS), the most common endocrinopathy in reproductive age, are characterized by increased cardiometabolic risk. Similar hormonal and metabolic changes were found in their siblings. The purpose of our study was to compare blood pressure-lowering and pleiotropic effects of lisinopril between sisters of women with PCOS and their unrelated peers. The study included two age-, body mass index-, and blood pressure-matched groups of women with grade 1 hypertension: 26 sisters of PCOS probands (Group 1) and 26 individuals without a family history of PCOS (Group 2), receiving 10-40 mg of lisinopril daily. Blood pressure, glucose homeostasis markers, plasma levels of lipids (androgens, estradiol, high-sensitivity C-reactive protein (hsCRP), homocysteine, fibrinogen, and uric acid), and urinary albumin-to-creatinine ratio (UACR) were measured before lisinopril treatment and 6 months later. At baseline, the study groups differed in insulin sensitivity, testosterone, free androgen index (FAI), hsCRP, homocysteine, and UACR. Blood pressure-lowering properties of lisinopril did not differ between the groups. The decrease in homocysteine and UACR, although observed in both groups, was stronger in Group 2 than in Group 1. Only in women without a family history of PCOS lisinopril improved insulin sensitivity and reduce hsCRP, fibrinogen, and uric acid. The remaining markers did not change throughout the study. Cardiometabolic effects of lisinopril correlated with testosterone, free androgen index, and changes in insulin sensitivity. The obtained results suggest that cardiometabolic effects of lisinopril may be slightly less pronounced in sisters of women with PCOS than in women without a family history of this disorder.

Vitamin D Status Determines Cardiometabolic Effects of Cabergoline in Women with Elevated Prolactin Levels: A Pilot Study

Both hyperprolactinemia and vitamin D deficiency appear to be associated with increased cardiometabolic risk. This study aimed to determine whether vitamin D status influences the cardiometabolic effects of cabergoline. The study included three matched groups of women with mild to moderate hyperprolactinemia: vitamin D-naive subjects with vitamin D insufficiency (group A), women with vitamin D deficiency/insufficiency successfully treated with vitamin D (group B), and vitamin D-naive individuals with normal vitamin D status (group C). Plasma prolactin, 25-hydroxyvitamin D, estradiol, glucose homeostasis markers, lipids, high-sensitivity C-reactive protein (hsCRP), fibrinogen, homocysteine, and uric acid, as well as the urinary albumin-to-creatinine ratio (UACR), were measured at study entry and after four months of cabergoline treatment. Although cabergoline reduced prolactin levels and increased estradiol levels in all study groups, the effect on prolactin was more pronounced in groups B and C compared to group A. In groups B and C, the drug enhanced glucose homeostasis, increased HDL-cholesterol, and decreased triglycerides, hsCRP, fibrinogen, homocysteine, uric acid, and UACR. In group A, only insulin resistance, hsCRP, and homocysteine were reduced by cabergoline. The effects on insulin sensitivity, HDL-cholesterol, triglycerides, hsCRP, fibrinogen, homocysteine, uric acid, and UACR were proportional to the decrease in prolactin and baseline levels of 25-hydroxyvitamin D. The obtained results suggest that vitamin D status determines cabergoline's cardiometabolic effects.

Pharmacological interventions for the treatment of insomnia: quantitative comparison of drug efficacy

PURPOSE

Although different forms of pharmacological intervention are often prescribed for insomnia disorder, the comparative efficacies among various drugs remain unclear. We therefore conducted this study to quantitatively compare the efficacy of various pharmacotherapies for insomnia by modeling.

METHODS

We searched PubMed, EMBASE and Cochrane Library databases for randomized placebo-controlled trials of insomnia medications that were conducted within a designated time period (from the inception dates to May 16, 2019). Pharmacodynamic models were established to describe the time course of changes from baseline in selected sleep parameters. Sleep quality and dropout rates were also compared by a single-arm meta-analysis.

RESULTS

In sum, 43 studies covering 44 trials (14,535 patients) were included in the analysis. The drugs evaluated included flurazepam, quazepam, temazepam, triazolam, eszopiclone, zaleplon, zolpidem, extended-release zolpidem, suvorexant, ramelteon and doxepin. The established models revealed eszopiclone had the highest efficacy in terms of sleep latency (SL), total sleep time (TST), and sleep quality, and was also associated with the lowest dropout rates. The effect of suvorexant on the parameter 'wake after sleep onset' (WASO) was significantly higher than that of the other drugs analyzed.

CONCLUSIONS

Each drug has its own characteristics in the treatment of insomnia, and this needs to be taken into consideration to meet individual clinical needs. These results serve as a quantitative supplement for clinical practice by reflecting the difference in efficacy of various drugs in the treatment of insomnia.

Prevalence-dependent decision limits for the early detection of type 2 diabetes mellitus in venous blood, venous plasma and capillary blood during glucose challenge

BACKGROUND

The glycemia decision limits recommended by WHO/ADA for type 2 diabetes detection are derived from clinical signs in advanced stages of the disease. Since insulin secretion patterns and sensitivitity are impaired at the beginning of type 2 diabetes, this stage may be better suited to identify decision limits with higher diagnostic efficiency than those currently applied.

METHODS

Oral glucose tolerance tests were performed in 300 subjects. Glucose concentrations were measured at 30-min intervals in venous plasma, venous blood and capillary blood. Insulin concentrations in venous plasma, an insulin sensitivity index and body mass index were used to indicate a type 2 diabetic state. A multiple logistic regression procedure was "trained" using only subjects "clearly" considered to be non-diseased or diseased based on an oral glucose tolerance test according to WHO criteria. This insulin algorithm was applied to the whole study group, leading to definitive classification into the non-diseased or the diseased group. This a posteriori classification was used to identify cutoff values with the highest diagnostic efficiency.

RESULTS

The diagnostic efficiency was significantly higher when decision limits lower than the WHO recommendations for glucose concentrations were applied in a preselected subpopulation and in all three sample systems tested, e.g., 9.49 mmol/L (171 mg/dL) for venous plasma and 8.94 mmol/L (161 mg/dL) for capillary blood in the 2-h post-load state. The optimized and WHO 2-h cutoff values corresponded to a disease prevalence of 28% and approximately 5% (20% in the fasting state), respectively. Diagnostic efficiency was higher in the 2-h post-load than in the fasting state. Combining fasting values with 2-h post-load values did not further improve the diagnostic efficiency. Glucose concentrations determined from capillary blood were as efficient as those from venous blood or plasma. The number of diabetic subjects detected differed considerably between capillary blood and venous plasma for the WHO/ADA cutoff values, but not for the optimized cutoff values.

CONCLUSIONS

The efficiency of type 2 diabetes diagnosis can be improved by optimizing cutoff values according to disease prevalence. Unexpectedly, the optimized 2-h post-load cutoff was lower for capillary blood than for venous plasma. It is proposed to identify a risk group e.g., by characteristics of the metabolic syndrome in which the 2-h post-challenge concentration is determined using lower cut-off values than presently recommended.

Placebo effects in primary insomnia

Placebo effects are commonly observed in insomnia clinical trials. With the advent of longer-term trials, such effects appear to be remarkably robust and durable. In this paper we review the classic factors that are believed to contribute to placebo effects and how these factors operate in insomnia randomized clinical trials. Beyond this we suggest that the episodic nature of insomnia may interact with patient preferences for intermittent dosing in such a way as to sustain placebo effects in the long term. An appreciation of the latter phenomenon may provide increased power to detect therapeutic outcomes and may be used to potentiate clinical gains.