The hormonal phenotype of Nonclassic 3 beta-hydroxysteroid dehydrogenase (HSD3B) deficiency in hyperandrogenic females is associated with insulin-resistant polycystic ovary syndrome and is not a variant of inherited HSD3B2 deficiency

To test our hypothesis that the hormonal phenotype of mild 3beta-hydroxysteroid dehydrogenase (HSD3B) deficiency in hyperandrogenic females (HF) is related to insulin-resistant polycystic ovary syndrome (PCOS), we compared insulin sensitivity and gonadotropin secretion in HF with compromised ( downward arrow ) adrenal HSD3B phenotype despite normal HSD3B2 genes (n = 6) to those in HF with classic PCOS (n = 9) of similar ages (14-36 yr). The same was examined in premature pubarche (PP) girls with (n = 4) and without the descending HSD3B phenotype (n = 5). The descending HSD3B phenotype was defined by ACTH-stimulated Delta(5)-precursor steroid levels and Delta(5)-precursors to Delta(4)-product steroid ratios higher than those in normal females (n = 30 for adult, n = 12 for pubertal). Classic PCOS HF had elevated testosterone levels and normal ACTH-stimulated hormonal profiles. The insulin sensitivity index determined by the frequently sampled iv glucose-tolbutamide test (FSIVGTT) in all HF with descending HSD3B phenotype and in all HF with classic PCOS, regardless of body mass index (BMI), was lower than in all eight normal BMI and five high BMI normal females. Integrated incremental insulin determined by FSIVGTT, the area under the curve for insulin, and fasting and 2 h glucose load insulin levels determined by an oral glucose tolerance test in both HF groups were higher (P < 0.01-0.0001) than those in normal females with normal or high BMI. LHRH-stimulated LH levels and LH/FSH ratios in both HF groups were higher (P < 0.01) than those in normal females. No statistical differences were found in the insulin sensitivity and gonadotropin parameter between the two PP girl groups. The insulin sensitivity index in each half of PP girls with the descending HSD3B phenotype was lower than or similar to that in control PP girls with a similar weight length index. The fasting glucose to insulin ratio in three of four PP girls with the descending HSD3B phenotype was lower than that in control PP girls, but one of four with the descending HSD3B phenotype had a higher fasting glucose to insulin ratio than the control PP girls. The findings of insulin sensitivity and gonadotropin data in both HF with the descending HSD3B phenotype and classic PCOS indicate significant insulin resistance and LH hypersecretion in both. These suggest that the descending HSD3B phenotype in HF is associated with a variant of insulin-resistant PCOS. The variable insulin sensitivity parameter in the small number of PP girls with the descending HSD3B phenotype warrants a further large scale study to examine this phenotype association with childhood insulin resistance.     

Metformin treatment for four years to reduce total and visceral fat in low birth weight girls with precocious pubarche

CONTEXT AND OBJECTIVE: A low birth weight (LBW) tends to be followed by overweight due to an excess of fat, including visceral fat. LBW girls with precocious pubarche (PP) (pubic hair < 8 yr) are at high risk for developing an adipose state of hyperinsulinemic androgen excess that leads toward early menarche. We explored the effects of insulin sensitization with metformin in LBW-PP girls. SETTING, DESIGN, PATIENTS, INTERVENTION: Prepubertal LBW girls with PP (mean body weight 2.4 kg; age 7.9 yr; body mass index 18.4 kg/m(2)) were studied. Girls were randomly assigned to remain untreated (n=19) or receive metformin for 4 yr (n = 19; 425 mg/d for 2 yr, then 850 mg/d for 2 yr). MAIN OUTCOMES: At the start and after 4 yr, height, weight, fasting insulin, glucose, IGF-I, testosterone, lipids, leptin, high molecular weight adiponectin, body composition by absorptiometry, abdominal fat partitioning (only 4 yr) by magnetic resonance imaging, and menarcheal status were determined. RESULTS: Metformin-treated girls gained on average 5.5 kg (or approximately 50%) less fat, after 4 yr were less insulin resistant and less hyperandrogenic, had lower IGF-I levels and a less atherogenic lipid profile, and were less likely to be post-menarcheal than untreated girls, whereas their gain in height, lean mass, and bone mineral density were similar. After 4 yr, untreated girls had more visceral fat, a higher ratio of visceral-to-sc fat, and a higher leptin-to-high molecular weight adiponectin ratio (all approximately 50% higher) than metformin-treated girls. CONCLUSION: Long-term metformin treatment appears to reduce total and visceral fat in LBW-PP girls, and to delay menarche without attenuating linear growth, thereby opening the perspective that adult height may be increased.     

Endocrine consequences of premature pubarche in post-pubertal Caucasian girls

BACKGROUND: It has been postulated that intrauterine undernutrition may predispose to serious endocrine consequences, including precocious pubarche (PP), functional ovarian hyperandrogenism and insulin resistance syndrome. OBJECTIVE: The aim of this study was to determine whether a history of PP was associated with the development of hyperandrogenism and/or metabolic consequences and to evaluate the effect of birth weight on this association. PATIENTS: The study population comprised 27 Caucasian girls with a history of PP and 25 healthy girls of similar age (17.4 +/- 1.3 vs. 17.7 +/- 0.9 years). RESULTS: Gynecological age, irregular menses and oral contraceptive use were similar in the two groups. PP girls showed an increased Ferriman-Gallway Score [median (range) 8 (4-17) vs. 6 (2-10), P = 0.02] and tended to have more previous history of acne. No statistical differences were found between the groups for mean testosterone (1.7 +/- 0.7 vs. 1.4 +/- 0.7 nmol/l, P = 0.49) and dehydroepiandrosterone sulphate concentrations (7.2 +/- 3.7 vs. 5.8 +/- 2.0 micromol/l, P = 0.15), but mean Delta4-androstenedione concentrations (7.3 +/- 2.4 vs. 4.9 +/- 2.1 nmol/l, P = 0.007) and free androgen index (8.5 +/- 9.7 vs. 3.6 +/- 3.9 IU, P = 0.003) were significantly increased in the PP group. All girls showed normal glucose tolerance with an oral glucose tolerance test. Derived insulin resistance parameters were not statistically different between the two groups and fasting lipids were comparable in both groups. There was no significant effect of birth weight on androgen levels in the PP girls. Moreover, none of the PP girls demonstrated the above-described association. CONCLUSIONS: Precocious pubarche could be the first sign of future functional ovarian hyperandrogenism but a link between this condition and intrauterine undernutrition or insulin resistance could not be demonstrated in this study.     

Evaluation of Glucose Metabolism and Cardiovascular Risk Factors in Prepubertal Girls with Premature Pubarche

Objective:Premature pubarche (PP) is a risk factor for metabolic syndrome (MS). The aim was to evaluate if glucose-insulin metabolism, cardiovascular risk factors, familial cardiovascular risk factors (FCVRF) created a risk for insulin resistance (IR) and if PP was a risk factor alone for MS in normal weight prepubertal girls with PP.Methods:Thirty-five prepubertal, non-obese girls with PP with normal birth weight and 35 age-matched control girls were evaluated for FCVRF, anthropometric measurements, blood pressure, lipid profile, fasting blood glucose-insulin, hemoglobin A1c (HbA1c), sex hormone binding globulin (SHBG), leptin, adiponectin, tumor necrosis factor-alpha (TNF-α), androgen levels, and bone age. Oral glucose tolerance test was performed in PP participants. Homeostasis model of assessment of IR (HOMA-IR), fasting glucose/insulin ratio, atherogenic index (AI), and free androgen index (FAI) were calculated. PP participants were further stratified by FCVRF.Results:HbA1c, lipid profile, testosterone, leptin, adiponectin, TNF-α, HOMA-IR, glucose/insulin ratio, AI, and fasting glucose-insulin levels were similar. In the PP group FAI was significantly higher (p=0.001), whereas SHBG was significantly lower (p=0.010) than the control group. Leptin levels of FCVRF+ and FCVRF- subgroups were 15.2±9.1 and 9.7±7.2 ng/mL, respectively and the difference was significant (p=0.016).Conclusion:As PP does not appear to be a risk factor alone for impaired glucose metabolism and IR in prepubertal non-obese girls with normal birth weight, it is our opinion that it is unnecessary to examine in detail such cases before puberty. Low SHBG levels in the PP group and high leptin levels in FCVRF+ subgroup might suggest that these may be predictive for MS in the future.     

Sensitization to insulin in adolescent girls to normalize hirsutism, hyperandrogenism, oligomenorrhea, dyslipidemia, and hyperinsulinism after precocious pubarche

Precocious pubarche in girls is often preceded by low weight at birth and followed by hirsutism, ovarian hyperandrogenism, and oligomenorrhea in adolescence, the latter usually being accompanied by dyslipidemia and hyperinsulinism, which are, in turn, two major risk factors for cardiovascular disease in later life. We hypothesized that insulin resistance may be a key pathogenetic factor in this sequence. We tested the hypothesis by assessing the effects of an insulin-sensitizing agent, metformin, given at a daily dose of 1275 mg for 6 months to 10 nonobese adolescent girls (mean age, 16.8 yr; body mass index, 21.9 kg/m2; birth weight, 2.7 kg) with hirsutism, ovarian hyperandrogenism (diagnosis by GnRH agonist test), oligomenorrhea, dyslipidemia, and hyperinsulinemia after precocious pubarche. Before the metformin trial, longitudinal studies in these girls had shown that hyperinsulinism was present at prepubertal diagnosis of precocious pubarche, and that it increased markedly in late puberty or early postmenarche. Metformin treatment was well tolerated and was accompanied by a marked drop in hirsutism score, insulin response to oral glucose tolerance test, free androgen index, and baseline testosterone, androstenedione, dehydroepiandrosterone, and dehydroepiandrosterone sulfate levels (all P < 0.01). During metformin treatment, the LH and 17-hydroxyprogesterone hyperresponses to GnRH agonist were attenuated (P < 0.01); serum triglyceride, total cholesterol, and low density lipoprotein cholesterol levels decreased; and high density lipoprotein cholesterol rose. All girls reported regular menses within 4 months. Withdrawal of metformin treatment was followed, within 3 months, by a consistent reversal toward pretreatment conditions. In conclusion, metformin treatment reduced hyperinsulinemia, hirsutism, and hyperandrogenism; attenuated the LH and 17-hydroxyprogesterone hyperresponses to GnRH agonist; improved the atherogenic lipid profile; and restored eumenorrhea in nonobese adolescent girls with a history of precocious pubarche. These observations corroborate the idea that insulin resistance may indeed be a prime factor underpinning the sequence from reduced fetal growth, through precocious pubarche, to adolescent endocrinopathies that are reminiscent of so-called polycystic ovary syndrome.     

Possible role of adiponectin and insulin sensitivity in mediating the favorable effects of lower body fat mass on blood lipids

AIMS: The objective of this study was to investigate the role of insulin sensitivity and serum adiponectin concentration as determinants, in middle-aged men, of the relationship between lower body fat and blood lipids after truncal fat has been accounted for. METHODS: Men (443) aged 39-65 yr, body mass index 18-43 kg/m(2), participated in the study. The following variables were measured: regional body fat distribution as assessed by dual-energy x-ray absorptiometry, maximal oxygen uptake, physical activity, fasting levels of serum adiponectin, triglycerides, and high-density lipoprotein- and total cholesterol. Plasma glucose and serum insulin were measured in the fasting state and after an oral glucose load. RESULTS: Lower body fat mass was inversely associated with serum triglycerides and total cholesterol and positively with serum high-density lipoprotein-cholesterol after adjustment for age, lean tissue mass, truncal fat mass, weight history, maximal oxygen uptake, and the level of physical activity (P < 0.0005). Serum adiponectin level and Matsudas insulin sensitivity index were positively intercorrelated, and both were positively correlated to lower body fat mass. When including adiponectin and insulin sensitivity in the analyses, the relationships between lower body fat mass and serum lipids were partly explained. CONCLUSION: For a given level of truncal fat mass, a large lower body fat mass is associated with an advantageous blood lipid profile, which may be partially mediated by the relationships to both insulin sensitivity and serum adiponectin level.     

Hyperinsulinaemia, dyslipaemia and cardiovascular risk in girls with a history of premature pubarche

Summary Girls with a history of premature pubarche, i. e. appearance of pubic hair before 8 years of age, show hyperinsulinism in response to an oral glucose tolerance test. As hyperinsulinaemia has a major role in dyslipaemia, and is considered an independent risk factor for cardiovascular disease, we assessed the patterns of plasma insulin concentration after a standard oral glucose tolerance test as well as fasting serum lipid, lipoprotein, and sex hormone-binding globulin concentrations in girls (n = 81) with premature pubarche compared with girls (n = 55) matched with them for stage and bone age to ascertain their metabolic states to identify those potentially at risk for the development of premature cardiovascular disease. Mean serum insulin concentrations were higher in patients at all pubertal stages, and associated with elevated serum triglyceride, very low density cholesterol and very low density triglyceride concentrations (p value range 0.04 to < 0.0001) but reduced sex hormone-binding globulin. Premature pubarche patients also displayed higher low density to high density lipoprotein cholesterol ratios compared with control subjects (p = 0.004 to 0.008). In conclusion, hyperinsulinaemia, decreased sex hormone-binding globulin concentrations and an unfavourable lipid pattern are common features in premature pubarche girls supporting the contention that atherogenic abnormalities composing the metabolic syndrome could start in childhood. To determine the clinical sequelae of such clustering of metabolic deviations, girls who were identified need to be followed up for the potential development of premature cardiovascular disease. [Diabetologia (1998) 41: 1057–1063] Received: 27 January 1998 and in final revised form: 11 May 1998     

Metformin treatment to prevent early puberty in girls with precocious pubarche

CONTEXT AND OBJECTIVE: Girls with precocious pubarche (PP, pubic hair at < 8 yr of age) are at high risk for early onset and rapid progression of puberty, in particular if their prenatal growth was restrained, i.e. low birth weight (LBW), and followed by rapid postnatal catch-up of weight gain. We postulated that insulin resistance contributes to early onset and rapid progression of puberty in LBW-PP girls and thus explored the puberty-delaying effects of insulin sensitization with metformin initiated shortly after PP diagnosis. SETTING, DESIGN, AND PATIENTS: The study population consisted of 38 prepubertal LBW girls with PP attributed to exaggerated adrenarche [mean body weight, 2.4 kg; age, 7.9 yr; body mass index (BMI), 18.4 kg/m(2)]. These girls were randomly assigned to remain untreated (n = 19) or to receive metformin (n = 19; 425 mg/d) for 2 yr. MAIN OUTCOME MEASURES: Pubertal staging, age at menarche, body composition by absorptiometry, fasting insulin, glucose, lipids, leptin, IGF-I, IGF-binding protein-1, testosterone, dehydroepiandrosterone sulfate, and SHBG were the main outcome measures. RESULTS: Metformin treatment was associated with a less adipose body composition (and lower serum leptin levels) and with a 0.4-yr delay in the clinical onset of puberty (Tanner B2; 9.5 vs. 9.1 yr; P < 0.01). These findings were corroborated by a delay of at least 1 yr in the puberty-associated rise of circulating IGF-I (P < 0.01). Available results also point to a metformin-associated delay of menarche (P < 0.02). Gain in height and lean mass was not divergent between study subgroups. CONCLUSION: The efficacy of early metformin treatment in PP girls is here extended to include not only a less adipose body composition after 2 yr but also a less advanced onset of puberty, whereas height gain is maintained. These findings open the perspective that, ultimately, metformin treatment may also prove to heighten the short adult stature of LBW-PP girls.     

Preteen insulin levels interact with caloric intake to predict increases in obesity at ages 18 to 19 years: a 10-year prospective study of black and white girls

We evaluated the associations of teenage insulin and adolescent diet with 10-year weight gain in an analysis sample of black and white girls matched for pubertal stage, body mass index (BMI) (or fat mass), and insulin at ages 9 to 10 years. We hypothesized that preteen insulin and insulin resistance would interact with dietary factors to positively predict increases in BMI. Furthermore, we hypothesized that increased insulin and insulin resistance, interacting with higher caloric intake during adolescence, would lead to greater increments in BMI in black girls than in white girls. Prospective 10-year follow-up was performed on 215 pairs of black and white schoolgirls matched at baseline by BMI (or fat mass), insulin, and pubertal stage, with repeated measures of body habitus, insulin, and dietary intake. When matched for BMI, black girls had higher fat-free mass and white girls had higher fat mass at ages 9 to 10 years. Black-white differences in caloric intake were not significant at ages 9 to 10 years, but black girls consumed more calories at age 19 years. Black girls consumed a greater percentage of calories from fat throughout. At age 19 years, black girls had higher BMI, fat mass index, and insulin. When matched at ages 9 to 10 years for fat mass, black girls were heavier, had higher BMI, and had greater fat-free mass. By ages 18 to 19 years, black girls continued to have higher BMI, but had accrued higher fat mass and a higher percentage of body fat. By stepwise multiple regression, 10-year increases in BMI were predicted by ages 9 to 10 years BMI, 10-year change in insulin, and a 3-way interaction between ages 9 to 10 years insulin, adolescent caloric intake, and race (higher in black girls) (all Ps < .0001). Insulin at ages 9 to 10 years interacts with caloric intake to increase BMI by age 19 years. There appear to be intrinsic black-white metabolic differences that lead to greater gains in fat during adolescence in black girls. Evaluating BMI and insulin at ages 9 to 10 years could identify girls (particularly black) who would optimally benefit from dietary and exercise interventions to avoid obesity.     

Influence of catch-up growth on IGFBP-2 levels and association between IGFBP-2 and cardiovascular risk factors in Korean children born SGA

Small for gestational age (SGA) at birth and postnatal growth pattern may have an impact on insulin resistance and body composition in their later life. Emerging evidence has indicated that insulin-like growth factor binding protein-2 (IGFBP-2) may be related to insulin sensitivity. The aim of this study was to evaluate insulin resistance and IGFBP-2 levels in SGA children, and to identify the effect of catch-up growth on IGFBP-2 concentration. Serum IGFBP-2 levels were measured in 103 Korean SGA children including 49 prepubertal and 54 pubertal subjects. Anthropometric values, fasting serum levels of metabolic parameters and insulin sensitivity indices were determined. Each prepubertal or pubertal group was subgrouped based on height or weight catch-up growth. The subgroups with weight catch-up showed higher values of BMI, body fat mass, percent body fat, and total cholesterol. Particularly in pubertal children, IGFBP-2 concentration was lower in the subgroup with weight catch-up. Catch-up growth in height did not affect insulin resistance and metabolic parameters. IGFBP-2 levels were inversely correlated with BMI, body fat mass, percent body fat, insulin and leptin levels in both prepubertal and pubertal groups. Additionally in the pubertal group, systolic blood pressure, cholesterol levels were related to IGFBP-2. A strong relationship between IGFBP-2, the insulin sensitivity index, and some cardiovascular risk factors was observed in children born SGA, suggesting that IGFBP-2 might be a promising marker for early recognition of insulin resistance, particularly in children with weight catch-up.     

Association between the insulin resistance of puberty and the insulin-like growth factor-I/growth hormone axis

To test the hypothesis that the relative insulin resistance of puberty is associated with changes in IGF-I levels, we compared IGF-I, IGF binding protein-3 (IGFBP-3), and IGFBP-1 levels to insulin resistance [M(lbm), milligrams glucose used per kilogram of lean body mass (LBM) per minute] measured during euglycemic, hyperinsulinemic clamp studies in 342 children and adolescents. IGF-I levels rose and fell during the Tanner stages of puberty in a pattern that closely followed the rise and fall of insulin resistance. IGF-I levels were significantly related to M(lbm) in boys (P = 0.0006) and girls (P = 0.02). IGF-I was significantly related to fasting insulin levels only in girls (P = 0.006; boys, P = 0.26), and this relation was significantly influenced in girls by body fat (P = 0.007), with the strongest association between IGF-I and fasting insulin seen in thin girls. IGFBP-1 correlated negatively with insulin resistance in both boys (P = 0.0004) and girls (P = 0.04), whereas IGFBP-3 correlated positively with insulin resistance in boys (P = 0.0004) but not girls (P = 0.85). These data suggest that the GH/IGF-I axis is an important contributor to the insulin resistance of puberty.     

Insulin sensitization for girls with precocious pubarche and with risk for polycystic ovary syndrome: effects of prepubertal initiation and postpubertal discontinuation of metformin treatment

Among girls with precocious pubarche (PP), those with low birth weight (LBW) are, even if nonobese, at risk for progression to polycystic ovary syndrome (PCOS) including hyperinsulinemic hyperandrogenism, dyslipidemia, dysadipocytokinemia, and central fat excess. Recently, we disclosed the efficacy of insulin sensitization with metformin to disrupt progression from PP to PCOS in formerly LBW girls who were postmenarche. In LBW-PP girls, we have now extended the exploration of early insulin sensitization therapy in two directions: 1) metformin therapy was started before puberty; and 2) we assessed the effects of metformin discontinuation in girls who had started metformin treatment after menarche. Prepubertal LBW-PP girls (n = 33; mean age, 8.0 yr; body mass index, 18.5 kg/m(2)) were randomly assigned to remain untreated or to receive metformin (425 mg/d) for 6 months. Postpubertal LBW-PP girls (n = 24; age, 12.4 yr; body mass index, 21.0 kg/m(2)) had been randomized (at -12 months) to remain untreated or to receive metformin (850 mg/d) for 12 months, at which time (0 month) a treatment cross-over was performed for 6 months. Fasting blood glucose and serum insulin, SHBG, dehydroepiandrosterone sulfate, androstenedione, testosterone, lipid profile, IL-6, and adiponectin were assessed at 0 and 6 months, as was body composition (by dual x-ray absorptiometry). In the prepubertal study (group A), comparisons of untreated vs. treated girls disclosed normalizing effects of metformin on SHBG, androstenedione, dehydroepiandrosterone sulfate, low and high density lipoprotein cholesterol, triglycerides, IL-6, adiponectin, total and abdominal fat mass, and lean body mass. In the postpubertal study (group B), treatment cross-over at 0 month was in each subgroup followed by a striking reversal in the course of the endocrine-metabolic state, adipocytokinemia, and body composition; all changes pointed to normalizing effects of metformin treatment. In conclusion, these two studies provide the first evidence that 1) prepubertal metformin therapy has normalizing effects on PCOS features in high risk girls with a combined history of LBW and PP; and 2) in adolescence, metformin's normalizing effects are reversed as soon as metformin therapy is discontinued.     

Androgenicity and obesity are independently associated with insulin sensitivity in postmenopausal women

An increase in androgenicity may contribute to the development of insulin resistance in postmenopausal women. Increased androgenicity in women has been found to be associated with the development of type 2 diabetes. In addition, obesity and central obesity are associated with greater androgenicity. Insulin sensitivity, androgenicity, and body composition were characterized in 34 nondiabetic postmenopausal women age 72 +/- 1 years (mean +/- SEM) to test the hypothesis that androgenicity is a predictor of insulin sensitivity independent of measures of obesity. Androgenicity was measured using levels of sex hormone-binding globulin (SHBG), total and free testosterone, dehydroepiandrosterone sulfate (DHEA-S), androstenedione, and free androgen index (FAI). Insulin sensitivity (S(I)) was determined from a frequently sampled intravenous glucose tolerance test. Body composition measures included body mass index (BMI) and dual energy x-ray absorptiometry measurements of total and central fat mass. S(I) was found to be associated with total fat mass (r = -.51, P =.002), central fat mass (r = -.62, P =.0001), BMI (r = -.55, P =.0008), SHBG levels (r =.65, P =.0001), and FAI (r = -.41, P =.01). SHBG levels were inversely correlated with central fat mass (r = -.59, P =.0002). Using multiple regression, SHBG and central fat mass were the only significant independent predictors of S(I), accounting for 50% of its variance (r =.71, P =.0001); total fat mass, BMI, total and free testosterone, DHEA-S, androstenedione, and FAI did not enter the model. We conclude that there is a significant association between insulin sensitivity and androgenicity in postmenopausal women that is independent of obesity. Interventions to decrease androgenicity may therefore be useful in improving insulin sensitivity in postmenopausal women.     

The pubertal timing controversy in the USA, and a review of possible causative factors for the advance in timing of onset of puberty

Previously used standards for the diagnosis of precocious puberty in girls no longer appear to be appropriate in the USA, in that a significant number of girls are being seen in paediatricians' offices with breast budding before 8 years of age. The timing of menarche, however, has changed little over the past few decades. Early maturing girls are more likely to become obese in adolescence and adulthood than normal or late maturing girls. Early maturing white girls are heavier at the onset of puberty, but this is not the case for African-American girls or boys of either race. Boys and girls with premature pubarche may be more hyperinsulinaemic than normal children, and girls with premature pubarche more likely to develop functional ovarian and adrenal hyperandrogenism. Early menarche is preceded by prepubertal hyperinsulinaemia. It is proposed that pubertal onset, although not necessarily the tempo of puberty, is influenced by hyperinsulinaemia and insulin resistance. If this hypothesis is correct, insulin resistance may be more prevalent in US children than previously recognized. An advance in timing of onset of puberty has not been noted in other countries, although it is likely that this phenomenon may become more prevalent as other countries adopt a more American lifestyle and diet.     

Anovulation in eumenorrheic,nonobese adolescent girls born small for gestational age: insulin sensitization induces ovulation,increases lean body mass,and reduces abdominal fat excess,dyslipidemia, and subclinical hyperandrogenism

Adolescent girls born small for gestational age (SGA) are at risk for anovulation, hyperinsulinism, subclinical hyperandrogenism, dyslipidemia, and central adiposity. Hyperinsulinemic insulin resistance has been proposed as a key pathogenetic factor underpinning these associations. We have tested this hypothesis in an intervention study by assessing the effects of insulin sensitization (metformin treatment, 850 mg/d for 3 months) in eumenorrheic, nonobese, anovulatory SGA adolescents [n = 13; mean birth weight, 2.3 kg; age, 15 yr; body mass index (BMI), 20.5 kg/m(2); >or=3 yr post-menarche] who were in a steady state (over approximately 6 months) for BMI, hyperinsulinism, subclinical hyperandrogenism, and dyslipidemia, and who presented a deficit of lean body mass and an excess of (truncal and abdominal) fat mass. Metformin treatment was accompanied by a drop in fasting insulin and serum androgens and by a less atherogenic lipid profile (all P 相似文献   

Body composition, fasting leptin, and sex steroid administration determine GH sensitivity in peripubertal short children.

Serum IGF-I levels in GH-treated subjects demonstrate a wide range of responsiveness to GH. However, the factors influencing GH sensitivity are not well known. The aim of this work was 1) to test whether body composition (determined by dual energy x-ray absorptiometry) or factors related to body composition (fasting blood glucose, FFA, C-peptide, leptin, and insulin sensitivity determined by an insulin tolerance test) influence GH sensitivity; and 2) to study the effect of sex steroid priming on GH sensitivity. We measured serum IGF-I at baseline and 24 h after a single administration of GH (2 mg/m(2)) in 60 healthy prepubertal and early pubertal children (height, -2.1 +/- 1.0 SD score). GH sensitivity, as estimated by the increase in serum IGF-I after GH administration (difference between stimulated and baseline serum IGF-I = delta IGF-I), was also determined after a short-term administration of oral ethinyl E2 in girls and im T in boys. The serum IGF-I concentration was 297 +/- 114 microg/liter at baseline and increased to 429 +/- 160 microg/liter, corresponding to a 46 +/- 29% increase over the baseline value (P < 0.0001, stimulated vs. baseline serum IGF-I). delta IGF-I was not different between gender or pubertal stage. There were positive correlations (P < 0.001) between delta IGF-I and adiposity (total body fat, r = 0.62; trunk fat, r = 0.62), fasting leptin (r = 0.64), and C-peptide (r = 0.54), and a negative correlation with fasting FFA (r = -0.33; P < 0.05) even after adjustment for age, gender, and pubertal stage. These factors remained significant independent predictors of the absolute as well as the percent increase in serum IGF-I in multiple regression analyses. Priming with T and ethinyl E2 had a similar stimulating effect on the serum GH peak in response to the insulin tolerance test. In boys, serum baseline IGF-I increased by 60%, and delta IGF-I was similar after vs. before T administration. By contrast, in girls, serum baseline IGF-I was similar, and delta IGF-I was 60% less after vs. before ethinyl E2 administration. This study indicates that 1) GH sensitivity is determined by fat mass, serum fasting leptin, C-peptide, and FFA; and 2) oral ethinyl E2 and im T have divergent effects on the IGF-I response to a single administration of GH.     

Insulin: in search of a syndrome.

The insulin resistance syndrome has been defined as the clustering of hypertension, dyslipidaemia and impaired glucose tolerance in subjects with high fasting plasma insulin concentrations. The latter are usually taken as a surrogate measure of insulin resistance of whole-body glucose disposal. Although hyperinsulinaemia and insulin resistance are reciprocally related to one another, the association is not very strong. In the data-pooling project of the European Group for the study of Insulin Resistance (EGIR), clamp-derived insulin sensitivity (as the M value) and fasting plasma insulin concentrations were available in 1308 non-diabetic subjects with a wide range of age and body mass index. In this cohort, hyperinsulinaemia (as the upper quartile of fasting plasma insulin distribution in the non-obese segment of the population) and insulin resistance (as the bottom quartile of M value in the same subgroup) were each present in approximately 40% of the whole population, but identified only partially overlapping (60%) subsets of individuals. When the subjects with insulin resistance but without hyperinsulinaemia (n = 198) were compared with the subjects with hyperinsulinaemia but without insulin resistance (n = 267), significant differences emerged in the respective clinical phenotypes. Thus, subjects with 'pure' insulin resistance had a more central fat distribution and presented evidence of excessive lipolysis and endogenous glucose production. In contrast, subjects with 'pure' hyperinsulinaemia had suppressed lipolysis, endogenous glucose production and insulin clearance, higher values of systolic blood pressure and lower values of serum HDL-cholesterol concentrations. The only abnormality common to both phenotypes was the presence of raised serum triglycerides concentrations. This analysis indicates that hyperinsulinaemia and insulin resistance identify partially different subgroups of individuals in a non-diabetic population, and suggests that hyperinsulinaemia and insulin resistance carry distinct pathogenic potential in terms of the components of the insulin resistance syndrome.     

Adiponectin before and after weight loss in obese children

Adiponectin is decreased in obesity and seems to be involved in insulin resistance. The influences of age, gender, puberty, and weight loss on adiponectin have not been studied in obese children. We measured body fat mass based on skinfold thickness, age, pubertal stage, gender, adiponectin, and insulin resistance (homeostasis model assessment) in 42 obese children. We analyzed adiponectin and homeostasis model assessment 1 yr later in these obese children and separated them into two groups according to degree of weight loss (decrease in sd score for body mass index, >or=0.5 vs. <0.5). Adiponectin was negatively correlated to percentage body fat (r = -0.44; P = 0.002), insulin resistance (r = -0.33; P = 0.016), and age (r = -0.41; P = 0.003). Adiponectin levels were significantly (P = 0.017) higher in pubertal girls compared with boys, but there was no significant difference in prepubertal children in respect to gender (P = 0.833). Adiponectin was significantly (P < 0.001) lower in pubertal compared with prepubertal children. The significant weight loss in 16 children was associated with a significant increase in adiponectin (P = 0.010) and a decrease in insulin resistance (P = 0.013), whereas there were no changes in the 26 children without significant weight loss. Adiponectin levels in obese children were negatively correlated to age, body fat, and insulin resistance and were decreased in puberty. Significant weight loss led to an increase in adiponectin levels and an improvement of insulin resistance.     

Body fat mass, body fat distribution, and pubertal development: a longitudinal study of physical and hormonal sexual maturation of girls.

The rate at which girls progress through the stages of puberty in relation to body fat mass and body fat distribution and its relation to their hormonal profiles was studied. Sixty-eight schoolgirls participated in a longitudinal study during 3 yr. The girls were divided into subgroups with increasing skinfold thicknesses and waist-hip ratio. They were also grouped depending on Tanner's breast development classification (M2 and M3). The age at M2 was only marginally correlated with the menarcheal age, but the age at M2 and the time interval from that age to menarche was negatively correlated. Age at the onset of puberty was not related to body fat mass or distribution. The rate of pubertal development after pubertal stage M3 was negatively related to the body fat mass. Age at M2 was only correlated with estrone (E1), while the rate of pubertal development was associated with higher FSH, E1, estradiol (E2), the fraction of E2 that was not bound to sex-hormone-binding globulin (non-sex-hormone-binding globulin bound E2) and androstenedione plasma levels at the onset of puberty. Body fat distribution, rather than body fat mass was related to the total and the non-sex-hormone-binding globulin bound plasma levels of E2 and testosterone at the onset of puberty. Changes in body fat distribution in early female puberty were chiefly related to the waist circumferences. We found no evidence that body fat mass or body fat distribution triggers the onset of puberty. Body fat distribution was related to early pubertal endocrine activity. Body fat mass was negatively related to the rate of pubertal development toward menarche, but no clear indications for an endocrine-related process is found. We conclude that onset of puberty and menarche are not parallel pubertal events, and that early pubertal plasma E1, E2 and androstenedione levels are predictors for the rate of pubertal development toward menarche. We propose that the control of the onset of puberty and maturation of the hypothalamic-pituitary gonadal axis, with regard to negative feedback control, are at least partially independent. This induces on the average a "catch up" pubertal maturation in girls with a late onset of puberty.