Effect of oral contraceptives on plasma glucose, insulin, and glucagon levels

The effect of ethinyl estradiol–cyproterone acetate treatment on homocysteine levels in women with polycystic ovary syndrome

OBJECTIVE

Women with polycystic ovary syndrome (PCOS) have multiple risk factors for cardiovascular disease. The cardiovascular risk marker homocysteine (Hcy) is elevated in women with PCOS. This prospective study investigated the effect of oral contraceptives containing ethinyl estradiol-cyproterone acetate (EE-CA) on serum Hcy levels in women with PCOS.

STUDY DESIGN

A total of 30 women with PCOS were enrolled in this prospective study. The diagnosis of PCOS was made according to the criteria of the Rotterdam PCOS consensus workshop group. All women took oral contraceptives containing EE/CA (35 microg/2 mg) for 3 months. Serum samples for Hcy, lipid profile and hormones were obtained during the early follicular phase (days 3-5) of the spontaneous or progestin-induced bleeding at baseline, and after the third treatment cycle.

RESULTS

Three months of EE-CA therapy significantly decreased the Hcy levels from 55.97 +/- 16.04 to 54.03 +/- 16.15 (P = 0.01). A significant correlation was observed between the Hcy and total and free testosterone levels (r = 0.44, P = 0.015 and r = 0.46, P = 0.001 respectively).

CONCLUSIONS

Although the decrease in Hcy levels with EE-CA therapy was statistically significant, further studies are necessary to determine the clinical benefit of this treatment.

Insulin resistance, the metabolic syndrome, diabetes, and cardiovascular disease risk in women with PCOS

Polycystic ovary syndrome is the most common endocrinopathy of reproductive aged women affecting 6-10% of the population. Traditionally considered a reproductive disorder manifesting as chronic anovulation, infertility, and hyperandrogenism, management has primarily focused on short-term reproductive outcomes. Recently, however, significant metabolic aspects in conjunction with longer-term health sequealae of PCOS have been recognized. The metabolic features are primarily related to underlying insulin resistance (IR), which is now understood to play an important role in both the pathogenesis and long-term sequelae of PCOS.

Insulin resistance, the metabolic syndrome, diabetes, and cardiovascular disease risk in women with PCOS

Polycystic ovary syndrome is the most common endocrinopathy of reproductive aged women affecting 6-10% of the population. Traditionally considered a reproductive disorder manifesting as chronic anovulation, infertility, and hyperandrogenism, management has primarily focused on short-term reproductive outcomes. Recently, however, significant metabolic aspects in conjunction with longer-term health sequealae of PCOS have been recognized. The metabolic features are primarily related to underlying insulin resistance (IR), which is now understood to play an important role in both the pathogenesis and long-term sequelae of PCOS.

Oestrogens and insulin secretion

There is a persistent perception that oestrogens have an adverse effect on carbohydrate metabolism. It might therefore be expected that their use would result in a corresponding increase in the incidence of diabetes. Recent evidence from clinical trials suggesting that women on postmenopausal oestrogen hormone replacement therapy (HRT) have a reduced incidence of type 2 diabetes therefore appears paradoxical. Short-term supraphysiological oestrogen administration has an adverse effect on glucose tolerance, resulting from suppression of first-phase insulin secretion and increased insulin resistance. Oestrogen-induced increases in glucocorticoid activity could account for these effects. Oestrogen-induced deterioration in glucose tolerance is, however, accompanied by a reduction in fasting glucose, an effect that could be accounted for by glucagon antagonism. These short-term effects contrast with long-term preservation of insulin secretion and glucose homeostasis by oestrogens. In animal studies, ovariectomy is associated with decreased insulin secretion and increased risk of diabetes, whereas oestrogen administration protects against diabetes and increases the insulin response to glucose. The mechanism is uncertain, but direct effects on the pancreas via steroid receptors or indirect effects via oestrogen-induced glucagon antagonism and subclinical increases in glucocorticoids and growth hormone could all contribute. Recent evidence that HRT increases the risk of cardiovascular disease suggests that it should not be used for the prevention of diabetes, but the mechanism responsible for this benefit merits further investigation and might lead to new therapies.

Effects of oral contraceptives on glucose flux and substrate oxidation rates during rest and exercise

We examined the effects of oral contraceptives (OC) on glucose flux and whole body substrate oxidation rates during rest (90 min) and two exercise intensities [60-min leg ergometer cycling at 45 and 65% peak O(2) uptake (Vo(2 peak))]. Eight healthy, eumenorrheic women were studied during the follicular and luteal phases before OC and the inactive and high-dose phases after 4 mo of a low-dose, triphasic OC. Subjects were studied in the morning 3 h after a standardized (308 kcal) breakfast. There were significant reductions in glucose rates of appearance and disappearance during exercise of both intensities with OC but not rest. There were no phase effects on substrate oxidation during rest or exercise. These results are interpreted to mean that, in women fed several hours before study, 1) OC decreases glucose flux, but not overall carbohydrate and lipid oxidation rates during moderate-intensity exercise; and 2) synthetic ovarian hormone analogs in the doses contained in OC have greater metabolic effects on glucose metabolism during exercise than do endogenous ovarian hormones.

The oral contraceptive pill: a revolution for sportswomen?

OBJECTIVES

To determine the effects of the oral contraceptive pill (OCP) on skeletal health, soft tissue injury, and performance in female athletes.

METHODS

A literature review was performed using literature retrieval methods to locate relevant studies.

RESULTS

Most female athletes primarily choose to use the OCP for contraceptive purposes, but cycle manipulation and control of premenstrual symptoms are secondary advantages of its use. The effect of the OCP on bone density in normally menstruating women is unclear, with some studies reporting no effect, others a positive effect, and some even a negative effect. The OCP is often prescribed for the treatment of menstrual disturbances in female athletes, and improvements in bone density may result. Whether the OCP influences the risk of stress fracture and soft tissue injuries is not clear from research to date. Effects of the OCP on performance are particularly relevant for elite sportswomen. Although a reduction in Vo2MAX has been reported in some studies, this may not necessarily translate to impaired performance in the field. Moreover, some studies claim that the OCP may well enhance performance by reducing premenstrual symptoms and menstrual blood loss. A fear of weight gain with the use of the OCP is not well founded, as population studies report no effect on weight, particularly with the lower dose pills currently available.

CONCLUSIONS

Overall, the advantages of the pill for sportswomen would appear to outweigh any potential disadvantages. Nevertheless, there is individual variation in response to the OCP and these should be taken into account and monitored in the clinical situation. Women should be counselled as to the range of potential benefits and disadvantages in order to make an informed decision based on individual circumstances.

The natural history of the metabolic syndrome in young women with the polycystic ovary syndrome and the effect of long-term oestrogen-progestagen treatment

OBJECTIVE

Little is known about the natural history of polycystic ovary syndrome (PCOS), although preliminary data indicate that affected women are more susceptible than the general population to diabetes and cardiovascular diseases at post-menopausal ages. The aim of this study was to follow-up all main features of the metabolic syndrome in a group of young women with PCOS and to investigate the long-term effects on metabolism and body composition of oestrogen-progestagen (OP) compounds, which are frequently used in these women to treat hyperandrogenism and related clinical features.

DESIGN

Long-term follow-up study.

SUBJECTS AND METHODS

Thirty-seven women with PCOS were re-evaluated 10.3 +/- 0.8 years (range 6-18 years) after their first assessments (age: before 19.8 +/- 4.9 years; after 29.9 +/- 4.4 years). When first examined, women were instructed to follow a hypocaloric diet if they were obese plus OP, if they agreed to such treatment. Main anthropometric parameters, basal sex hormones and lipids, fasting and glucose-stimulated glucose and insulin levels and several clinical data were recorded before and after follow-up.

RESULTS

In the whole group of women with PCOS we found no changes in body weight and fat mass, whereas both the waist-to-hip ratio and the waist-to-thigh ratio were significantly reduced. No significant changes occurred in mean fasting and glucose-stimulated glucose and insulin concentrations, whereas a significant increase in high-density lipoprotein-cholesterol was found. No significant changes occurred in testosterone levels. During the follow-up period 16 women took OP for an average of 97 +/- 18 months (range 12-180 months) (OP-users) whereas 21 women never took OP (non-OP-users). All OP-users were still taking OP when re-evaluated at the follow-up examination. With respect to baseline values, body mass index was higher in non-OP-users than in their counterparts. Waist circumference (P < 0.025), the waist-to-hip (P < 0.05) and the waist-to-thigh (P < 0.01) ratios decreased significantly only in the OP-users. In addition, percentage changes in waist circumference (P < 0.05) and waist-to-hip ratio (P < 0.05) during the follow-up period were significantly different between the groups. Glucose tolerance (as area under the curve (AUC)) improved (P < 0.05) in OP-users but not in non-OP-users. Moreover, compared to baseline values, basal insulin levels were significantly (P < 0.01) reduced in OP-users but not in non-OP-users. On the contrary, no significant change was found in insulinAUC in the former, whereas it significantly increased (P < 0.05) in the latter. Accordingly, fasting C-peptide decreased (P < 0.05) in OP-users, whereas both fasting (P < 0.01) and stimulated (P < 0.01) C-peptide significantly increased in non-OP-users. Changes in fasting or stimulated insulin and C-peptide in non-OP-users were not associated with parallel changes in testosterone levels. Total cholesterol and triglycerides did not change in either group, but HDL-cholesterol increased (P < 0.05) only in OP-users. Sex hormone-binding globulin concentrations increased significantly (P < 0.01) in OP-users, without any significant change in non-OP-users. Testosterone concentrations did not change significantly in either group, but the testosterone: SHBG ratio significantly decreased in OP-users (P < 0.05) but not in the non-OP-users. Among the clinical features, acanthosis nigricans significantly (P < 0.01) worsened in non-OP-users but not in the OP-users, without any significant change in the hirsutism and acne scores. Pregnancy rates during the follow-up were similar in both groups.

CONCLUSIONS

These data indicate that hyperinsulinaemia and insulin resistance tended to worsen spontaneously in women with PCOS, without any worsening of the hyperandrogenism. Long-term oestrogen-progestagen treatment countered this tendency, probably because it improved the pattern of body fat distribution, by reducing abdominal fat depots.

The effects of hormonal replacement therapy on insulin sensitivity in surgically postmenopausal cynomolgus monkeys (Macaca fascicularis)

OBJECTIVE

Our purpose was to evaluate the effect of hormone replacement therapy on insulin resistance in postmenopausal cynomolgus monkeys (Macaca fascicularis).

STUDY DESIGN

We studied 37 surgically postmenopausal cynomolgus monkeys that were fed a moderately atherogenic diet for 12 weeks with either no treatment (control), conjugated equine estrogens, medroxyprogesterone acetate, combination conjugated equine estrogens and medroxyprogesterone acetate, or tamoxifen. Insulin sensitivity and glucose effectiveness were determined by the frequent-sampling intravenous tolerance test by means of the minimal model analysis.

RESULTS

There were no differences in body weight, total plasma cholesterol, or body fat distribution between control and conjugated equine estrogens, medroxyprogesterone acetate, or combination treatment groups. However, compared with control animals (insulin sensitivity = 5.9 +2- 1.2 x 10(-4) min-1 microU-1 ml) or conjugated equine estrogens treatment (6.3 +/- 1.1 x 10(-4) min-1 microU-1 ml) insulin sensitivity was significantly decreased in animals treated with medroxyprogesterone acetate (2.9 +/- 0.4 x 10(-4) min-1 microU-1 ml, p < 0.001) or conjugated equine estrogens and medroxyprogesterone acetate (2.8 +/- 0.6 x 10(-4) min-1 microU-1 ml, p < 0.001). Although insulin sensitivity was shown to be decreased in the tamoxifen-treated animals (insulin sensitivity = 4.6 +/- 0.6 x 10(-4) min-1 microU -1 ml), the difference was not statistically significant compared with the control or conjugated equine estrogens-treated animals. No significant differences were seen for glucose effectiveness comparing control animals (glucose effectiveness = 0.043 +/- 0.006 min-1) to animals treated with medroxyprogesterone acetate (glucose effectiveness = 0.046 +/- 0.009 min-1), conjugated equine estrogens and medroxyprogesterone acetate (0.048 +/- 0.008 min-1) or tamoxifen (0.039 +/- 0.006 min-1).

CONCLUSION

These results suggest that progestins alone or in combination with estrogens can induce insulin resistance in postmenopausal monkeys while having no effect on plasma lipid concentrations or glucose effectiveness.

Insulin responses following glucose administration in menstruating women

OBJECTIVE

The aim of the study was to investigate changes in insulin sensitivity during the menstrual cycle, in a group of regularly menstruating black African women.

METHOD

Insulin responses to intravenous glucose (300 mg/kg) were assessed, for up to 3 h, in 3 groups of age- and body mass-matched non-obese sedentary Nigerian women: Group A, 7 women in the menstrual follicular phase; Group B, 7 women in the menstrual luteal phase; C, 7 men.

RESULT

Women in the menstrual luteal phase had the greatest integrated first-phase insulin response and insulin/glucose ratios, much higher than the similar values for these variables obtained in other groups. This suggests that the menstrual luteal phase is associated with relative insulin resistance.

CONCLUSION

Black African women in the menstrual luteal phase demonstrate an exaggerated insulin response to an acute glucose load and are thus relatively insulin-insensitive. This confirms previous observations in Caucasians.

Carbohydrate metabolism before and after Norplant removal

Changes in carbohydrate metabolism, measured by oral glucose tolerance test, were studied in Norplant users before and after removal. The mean area under the glucose curve rose from 24.7 min mmol/L before Norplant insertion to 35.1 min mmol/L before removal and decreased to 26.1 min mmol/L four weeks after Norplant removal. The areas before insertion and after removal were not statistically different (95% confidence interval -3.3 to 0.56, P = 0.16). The mean areas under the insulin curves before insertion (53.14 min uU/L) and after removal (59.46 min uU/L), however, were significantly different (95% confidence interval -7.64 to -5.0, P less than 0.0001). We conclude that changes in carbohydrate metabolism induced by Norplant are reversible once the implants are removed. While the changes in glucose induced by Norplant returned to pre-insertion levels within 4 weeks after removal, insulin changes were slower to return to pre-insertion values.

The effect of continuous subdermal levonorgestrel (Norplant) on carbohydrate metabolism

Blood glucose and plasma insulin levels during an oral glucose tolerance test were measured in 20 women using continuous subdermal levonorgestrel (Norplant) for contraception over a 12-month period. Changes in carbohydrate metabolism occurred as early as 1 month but were most marked after 6 months. After 1 month the area under the glucose and insulin curves increased by 12.3% and 37.7%, respectively. This increase was more marked by 6 months, but by 12 months it was significantly less marked. Although changes in the blood glucose and plasma insulin levels at different times during the oral glucose tolerance test occurred, they were all within normal limits for normal women. The peak blood glucose and insulin levels after insertion of the implant occurred 60 minutes after the glucose load, as opposed to 30 minutes before insertion. Apart from this, there was a significant delay in the return of these levels to fasting values. We conclude that this product, like any other progesterone-containing contraceptive, alters carbohydrate metabolism, but these alterations are not clinically significant in normal women. It is, however, possible that in potential cases of diabetes it may predispose to frank diabetes.

Interindividual comparability of blood glucose alterations after meals of complex carbohydrates

Young male and female probands underwent an DGTT (oral glucose tolerance test) using a glucose load of 1 g/kg b.wt. The alterations in blood glucose levels were checked and plotted by a Biostator. A week later groups of those probands were fed an isocaloric meal of complex CH, namely either potatoes, noodles or white bread. The resulting BG curves were also checked by a Biostator. It turned out that: 1. the shapes of the BG curves after glucose load were not interindividually comparable. 2. there was neither a similarity of the shapes of the BG curves within the groups after any of the different CH levels. 3. But if one compares the shape of the BG curves after glucose load and after a meal of any of the complex CH of one and the same person, there is a striking similarity in those curve shapes. The differences between them lie just in the mostly lower BG values of the curves after CH meals compared with those after glucose load. 4. Therefore the resulting graph of both of those curves is in all observed cases a straight line with a probability better than 0.001, called OGTT-calibrating resulting graph.

Effects of estradiol and progesterone on diabetes-associated utero-ovarian atrophy in C57BL/KsJ (db/db) mutant mice

The modulating effects of estradiol (E: 1 microgram/3.5 days) and progesterone (P: 2 mg/3.5 days) on the obesity and hyperinsulinemic and hyperglycemic components of the diabetes-obesity syndrome in female C57BL/KsJ (db/db) mice, which includes cellular atrophy and adiposity in the reproductive tract, were examined and compared to corresponding control (+/?) parameters. All control and diabetic mice received oil (vehicle control), E, or P treatments starting at 4 weeks of age. Body weight, serum insulin levels, blood glucose concentrations, and utero-ovarian lipoprotein lipase activities were analyzed at 8 and 16 weeks of age and related to the ultrastructural changes in the steroid-sensitive uterine epithelium during the treatment period. Neither E nor P had any effect on body weights in (+/?) or (db/db) mice. The pronounced diabetes-associated elevation in serum insulin levels was enhanced by E, and suppressed by P, in 16-week-old (db/db) mice as compared with controls. By 16 weeks of age, the E therapy normalized blood glucose levels in diabetic mice to control levels, whereas P was ineffective in modulating the hyperglycemia. The reduction in blood glucose levels in E-treated diabetic mice correlated temporally with the return of normal intracellular structure including the disappearance of intracellular lipid vacuoles characteristic of uterine epithelium cells of (db/db) mice. The diabetes-induced rise in utero-ovarian lipoprotein lipase activity was normalized by P-therapy. The reduction in utero-ovarian lipoprotein lipase activity coincided temporally with the demonstrated intracellular reorganization in (db/db) reproductive tract tissues.(ABSTRACT TRUNCATED AT 250 WORDS)

Carbohydrate metabolic studies during twelve months of treatment with a low-dose combination oral contraceptive

Carbohydrate metabolism was evaluated in twenty healthy women volunteers using a low-dose combination oral contraceptive (OC) containing 30 micrograms of ethinyl estradiol and 500 micrograms of dl-norgestrel by measurement of serum glucose and insulin levels during 3-hour oral glucose tolerance test (OGTT) before and after 3, 6 and 12 months of medication. There were no significant differences in body weight or blood pressure between pretreatment and posttreatment. Fasting serum glucose levels were slightly reduced, though not significantly, during all periods of treatment. But serum glucose levels were increased at 1, 2 and 3 hours in association with high insulin responses during OGTT in all periods of OC therapy, indicating mild to moderate insulin resistance. These data suggest that the low-dose combination OC used in the study exerts alterations on carbohydrate metabolism in women during one year of OC use.

Metabolic effects of three new low-dose pills: a six-month experience

We evaluated the effects on glucose and lipid metabolism in 57 healthy volunteers randomly assigned to one of three low-dose oral contraceptives: two monophasic (desogestrel + ethinylestradiol, EE, and cyproterone acetate + EE) and one triphasic (gestodene + EE) contraceptives. Glucose and insulin responses during OGTT were slightly affected by the cyproterone pill. The insulin area/glucose area ratio and HbA1c level were unchanged in all women. No preparation affected total and LDL-cholesterol levels. Triglycerides rose in all groups, while HDL-CH did only in women taking the two monophasic pills. The three low-dose pills assessed in this study have negligible effects on glucose and lipid metabolism.

Alterations in carbohydrate metabolism as they apply to reproductive endocrinology

This review has characterized the current state of knowledge of four clinical situations in which an interrelationship of gynecology, endocrinology and carbohydrate metabolism is recognized. The literature contains conflicting descriptions of changes in glucose homeostasis during the menstrual cycle and while using birth control pills. Physiologic changes in receptor number have been demonstrated in each of these situations, so failure to observe differences using glucose tolerance testing may reflect an in vivo homeostatic response to changes in these hormone levels. Thus, in vivo identification of alterations in carbohydrate metabolism induced by endogenous or exogenous steroids may require utilization of models that prevent these homeostatic mechanisms. The association between hyperandrogenism and hyperinsulinism has been better characterized, but the relationship is complicated by the frequent coexistence of obesity. The association may be due to insulin-stimulated ovarian androgen production, and insulin insensitivity may reflect a postreceptor defect. Insulin and its metabolic effects have also been implicated in ovulatory dysfunction in women with diabetes mellitus and identified as a factor affecting all levels of the hypothalamic-pituitary-ovarian axis. A clearer understanding of these relationships and their application to clinical management await further study.

Impaired glucose tolerance in women using oral contraceptives: United States, 1976-1980

Based on 75-g oral glucose tolerance test results from the second National Health and Nutrition Examination Survey (1976-1980), women 20-44 years reporting the use of oral contraceptives (OCs) had decreased glucose tolerance compared with women not using OCs in this age group. Estimates of decreased glucose tolerance after adjustment for age and body mass index were 15.4% (95% CI, 7.6-23.2%) in OC users vs 6.3% (95% CI, 4.5-8.1%) in nonusers. Oral contraceptive use was associated with elevations in 1 and 2 hour plasma glucose concentrations. The mean adjusted difference between OC users and nonusers at 1 and at 2 hours postchallenge was 14 and 13 mg/100 ml, respectively. Characteristics of study nonrespondents vs respondents were analyzed to estimate potential bias due to nonresponse. No appreciable biases were found, but this does not rule out the possibility that some bias may exist.

Carbohydrate metabolism in women who used oral contraceptives containing levonorgestrel or desogestrel: a 6-month prospective study

Blood glucose and pyruvate, plasma insulin, and glucagon levels as well as erythrocyte insulin receptors were measured during an oral glucose tolerance test in 38 normal women before and after 6 months' use of one of three new oral contraceptives containing low doses of 19 nortestosterone-derived progestogens, levonorgestrel, and desogestrel. A slight deterioration of glucose tolerance was observed, with the area under the glucose curve increasing by only 7%, 9%, and 12% after Ovidol (Aaciphar SA, Brussels, Belgium), Marvelon (Organon, SA, Brussels, Belgium), and Trigynon (Schering SA, Brussels, Belgium) administration, respectively. We did not find any argument in favor of the development of a state of insulin resistance in women using these compounds, because erythrocyte receptor binding was not modified and plasma insulin responses to glucose were decreased. The glucose-induced suppression of plasma glucagon levels seemed less effective for treatment with the desogestrel-containing preparations than with the levonorgestrel-containing oral contraceptives.

Prevalence and trends in oral contraceptive use in premenopausal females ages 12-54 years, United States, 1971-80

Data from the second National Health and Nutrition Examination Survey (NHANES II) were analyzed to estimate the prevalence of oral contraceptive use in the United States, 1976-80. The overall unadjusted prevalence of oral contraceptive use was 16.7 per cent for premenopausal females ages 12-54 years (19.2 per cent for ages 15-44 years). Approximately 8.7 million females (95 per cent confidence interval, 6.9-10.5 million) were oral contraceptive users at the midpoint of NHANES II (March 1978). Comparison to the NHANES I, conducted in 1971-74, indicated a stable number of overall oral contraceptive users in the US population during the 1970s, with shifts in certain age groups: oral contraceptive use increased for females ages 12-19 years and decreased for females ages 20-49 years. The overall age-adjusted prevalences indicated a 2 per cent (95 per cent CI, 0.2-3.8 per cent) decline in oral contraceptive use from the early to the late 1970s. The NHANES provides comparative data and supports findings from another national survey showing a decrease in the per cent of females using oral contraceptives during 1973-82. Trends in oral contraceptive use are also presented by race, poverty level, rural-urban residence, marital status, and education level.

Pregnancy and diabetes: the maternal response

Pregnancy places remarkable stresses on maternal carbohydrate metabolism and pancreatic insulin reserves. The normal mammal responds to pregnancy by increasing pancreatic islet size and insulin secretion. Pregnancy also causes alterations in concentrations of metabolic fuels in maternal circulation. These changes are partly attributed to gestational increases of estrogen, progesterone and human chorionic somatomammotropin, and are thought to provide a proper metabolic and hormonal incubation medium for the fetus. Conversely, the compromised pancreas of the diabetic is unable to meet the additional demands of pregnancy, and carbohydrate metabolism deteriorates. The character of these metabolic changes depends on the time of gestation and the type of diabetes mellitus.