The use of the intravenous glucose tolerance test to evaluate nonobese hyperandrogenemic women

Plasma apelin levels in patients with polycystic ovary syndrome

OBJECTIVE

The aim of the study was to evaluate plasma apelin levels in patients with polycystic ovary syndrome (PCOS) and healthy controls.

MATERIAL AND METHODS

Plasma apelin levels, serum lipid levels, serum hormone levels, and homeostasis model assessment-insulin resistance (HOMA-IR) values of 32 patients with PCOS and 31 healthy women forming the control group were checked.

RESULTS

Plasma apelin levels of the PCOS group (0.350±0.083 ng/ml) were significantly higher than those of the control group (0.246±0.045 ng/ml) (p<0.001). No significant correlation was detected between apelin levels and biochemical or clinical data in PCOS group.

CONCLUSION

Plasma apelin levels were significantly higher in PCOS patients.

Characteristics of polycystic ovarian syndrome and relationship with ghrelin in adolescents

OBJECTIVE

Some points of pathogenesis in polycystic ovarian syndrome (PCOS) are still unknown. In this study we evaluated the characteristics of this disease and its relationship with ghrelin in adolescence.

DESIGN

A prospective case control study was designed. Four groups: obese PCOS (n = 13), lean PCOS (n = 13), obese control (n = 10) and lean control (n = 10) were formed. Oral glucose tolerance tests (OGTT) were performed on all subjects. Laboratory and clinical features of groups were compared.

SETTING

University pediatric endocrinology clinic.

PARTICIPANTS

Adolescents with PCOS.

INTERVENTIONS

None.

MAIN OUTCOME MEASURES

Insulin resistance, ghrelin, delta ghrelin (difference of ghrelin between basal and 120(th) minute after OGTT), androgens

RESULTS

Insulin resistance ratios were 93.3%, 46.6%, 50% in obese PCOS, lean PCOS and obese controls respectively. Ghrelin levels were lower in obese PCOS group but statistically different only between obese and lean PCOS groups. Ghrelin was correlated negatively with HOMA-IR (P < 0.001), 17 OH progesterone (P = 0.05), total (P = 0.015) and free testosterone (P = 0.013). Ghrelin suppression was blunted in PCOS groups. Ghrelin suppression ratios after glucose load were 24.4%, 28.7%, 36%, 35% obese PCOS, lean PCOS, obese control and lean control groups respectively.

CONCLUSION

Low ghrelin levels in obese PCOS patients, correlations between insulin resistance, androgens and ghrelin, blunted suppression of ghrelin after glucose load in PCOS have been considered as evidences of ghrelin role in pathogenesis of this syndrome.

Comparison of hormonal and metabolic markers after a high-fat, Western meal versus a low-fat, high-fiber meal in women with polycystic ovary syndrome

OBJECTIVE

To determine the effect of meal composition on postprandial T levels in women with polycystic ovary syndrome (PCOS).

DESIGN

Randomized, crossover design.

SETTING

Academic research center.

PATIENT(S)

Fifteen women with PCOS.

INTERVENTION(S)

We evaluated changes in T, sex hormone binding globulin (SHBG), DHEAS, cortisol, glucose, and insulin for 6 hours after a high-fat, Western meal (HIFAT) (62% fat, 24% carbohydrate, 1 g fiber) and an isocaloric low-fat, high-fiber meal (HIFIB) (6% fat, 81% carbohydrate, 27 g fiber).

MAIN OUTCOME MEASURE(S)

Change in T levels.

RESULT(S)

Testosterone decreased 27% within 2 hours after both meals. However, T remained below premeal values for 4 hours after the HIFIB meal and 6 hours after the HIFAT meal. Insulin was twofold higher for 2 hours after the HIFIB meal compared with the HIFAT meal. Glucose was higher for 1 hour after the HIFIB meal compared with the HIFAT meal. DHEAS decreased 8%-10% within 2-3 hours after both meals, then increased during the remainder of the study period. Cortisol decreased during the 6-hour period after both meals.

CONCLUSIONS

Diet plays a role in the regulation of T levels in women with PCOS. Further studies are needed to determine the role of diet composition in the treatment of PCOS.

Disturbances in insulin secretion and sensitivity in women with the polycystic ovary syndrome

Insulin resistance, defined as a diminished effect of a given dose of insulin on glucose homeostasis, is a highly prevalent feature of women with PCOS. Insulin resistance in PCOS is closely associated with an increase in truncal-abdominal fat mass, elevated free fatty acid levels, increased androgens, particularly free testosterone through reduced SHBG levels, and anovulation. The causes for insulin resistance in PCOS are still unknown. One line of evidence suggests that an increase in truncal-abdominal fat mass and subsequently increased free fatty acid levels induce insulin resistance in women with PCOS. Increased effects of corticosteroids and a relative reduction in oestrogen and progesterone seem to be involved in the aberrant body fat distribution. Conversely, there are also results supporting primary, genetic target cell defects as a cause of insulin resistance in PCOS. An explanation for these seemingly contradictory results could be that the group of women with PCOS is heterogeneous with respect to the primary event in carbohydrate/insulin disturbances. Also insulin secretion in PCOS is characterized by heterogeneity. At one end of the spectrum is a large subgroup of mainly obese women with reduced insulin secretion, which appears to result from failure of the beta cells to compensate for insulin resistance in susceptible women, resulting in glucose intolerance and NIDDM. In the insulin-resistant patients with normal glucose tolerance, most of the hyperinsulinaemia is probably due to secondarily increased insulin secretion and decreased insulin degradation. However, a component of the increased first-phase insulin release is not due to measurable insulin resistance. Notably, this is also found in lean women with normal insulin sensitivity, and is not reversed after weight reduction, in contrast to the findings for insulin resistance. The implications of this enhanced insulin release are not fully clear, but it may tentatively be associated with carbohydrate craving and subsequently increased risks for development of obesity and insulin resistance. It may represent a primary disturbance of insulin secretion in PCOS or may be associated with the perturbed steroid balance in anovulation. The insulin-androgen connection in PCOS appears to be amplified by several different mechanisms, notably in both directions, the initiating event probably varying between individuals. Thus insulin increases the biological availability of potent steroids, primarily testosterone, through the suppression of SHBG synthesis. Insulin is also involved as a progonadotrophin in ovarian steroidogenesis, with the possible net result of interfering with ovulation and/or increasing ovarian androgen production in states of hyperinsulinaemia. Conversely, testosterone may indirectly contribute to insulin resistance through facilitating free fatty acid release from abdominal fat, but perhaps also through direct muscular effects at higher serum levels. It seems likely that this constitution, presumably genetic, would provide evolutionary advantages in times of limited nutrition, given the energy-saving effects of insulin resistance. Hypothetically, hyperinsulinaemia (primary) could provide a stimulus to ensure intake of nourishment, but unlimited food supplies could in some cases initiate a vicious 'anabolic' circle, in which several of the proposed amplifying mechanisms between insulin and androgens--in both directions--could take part.

Glucagon stimulation test: assessment of beta-cell function in gestational diabetes mellitus

OBJECTIVE

Because women with gestational diabetes mellitus have a risk of up to 60% for the later development of type II diabetes, we used the intravenous glucagon stimulation test to evaluate beta-cell function in pregnant women.

PATIENTS

Twenty-seven pregnant women with one or more risk factors for gestational diabetes had an intravenous beta-cell stimulation test. Glucose, C-peptide and insulin levels were measured at baseline and 5, 10 and 15 min after the administration of 1 mg glucagon. The women were classified using the 75-g oral glucose tolerance test according to World Health Organization criteria. During the oral glucose tolerance test glucose, C-peptide and insulin levels were measured at baseline and at 2 h.

RESULTS

Insulin and C-peptide responses were significantly lower in pregnant women with impaired glucose tolerance and diabetes compared with women with normal glucose tolerance.

CONCLUSION

This study shows gradually decreasing insulin secretion from normal to subnormal in pregnant women without and with glucose intolerance, and diabetes mellitus, respectively.

The relation between clinical manifestations of polycystic ovary syndrome and beta-cell function

OBJECTIVE

Hyperandrogenism in patients with polycystic ovary syndrome has been shown to correlate with hyperinsulinaemia of insulin resistance. We have investigated if basal levels of insulin and the response to the intravenous administration of glucagon can reveal insulin resistance in patients with polycystic ovary syndrome.

PATIENTS

Nine obese (BMI > 25 kg/m2) and nine non-obese (BMI 19-25 kg/m2) women with PCOS, chosen from a population of 91 women attending the infertility clinic, and 19 normally cycling women (seven obese, 12 non-obese) were studied. Oligo or amenorrhoea, hirsutism, and 12 or more follicles in a given ovary were selection criteria.

MEASUREMENTS

Glucagon, 1 mg, was given intravenously to 18 of the 91 women and to the control subjects. Blood was taken at -5, 0, 5, 10 and 15 minutes for measurements of integrated areas under the response curve for insulin, C-peptide and glucose, respectively. Basal blood samples were drawn for fasting insulin, C-peptide, glucose, testosterone, sex hormone-binding globulin (SHBG), free fatty acids and IGF-I measurements. The free androgen index was calculated according to the formula FAI = testosterone x 100/SHBG.

RESULTS

There were no significant differences in maximal increment and area under the response curve for glucose, C-peptide and insulin. FAI was significantly higher in all patients with features of polycystic ovary syndrome. However, fasting insulin levels were significantly higher only in obese patients when compared with obese control subjects and lean patients.

CONCLUSIONS

The administration of 1 mg glucagon i.v. did not distinguish patients with polycystic ovary syndrome from control subjects. The mild insulin resistance of polycystic ovary syndrome is related only to obesity and is therefore unlikely to play an important role in the hyperandrogenism associated with the syndrome.