The effect of residual beta cell activity on menstruation and the reproductive hormone profile of insulin-dependent diabetics

Female reproduction and type 1 diabetes: from mechanisms to clinical findings

BACKGROUND

The functional reproductive alterations seen in women with type 1 diabetes (T1D) have changed as therapy has improved. Historically, patients with T1D and insufficient metabolic control exhibited a high prevalence of amenorrhea, hypogonadism and infertility. This paper reviews the impact of diabetes on the reproductive axis of female T1D patients treated with modern insulin therapy, with special attention to the mechanisms by which diabetes disrupts hypothalamic-pituitary-ovarian function, as documented mainly by animal model studies.

METHODS

A comprehensive MEDLINE search of articles published from 1966 to 2012 was performed. Animal model studies on experimental diabetes and human studies on T1D were examined and cross-referenced with terms that referred to different aspects of the gonadotropic axis, gonadotrophins and gonadal steroids.

RESULTS

Recent studies have shown that women with T1D still display delayed puberty and menarche, menstrual irregularities (especially oligomenorrhoea), mild hyperandrogenism, polycystic ovarian syndrome, fewer live born children and possibly earlier menopause. Animal models have helped us to decipher the underlying basis of these conditions and have highlighted the variable contributions of defective leptin, insulin and kisspeptin signalling to the mechanisms of perturbed reproduction in T1D.

CONCLUSIONS

Despite improvements in insulin therapy, T1D patients still suffer many reproductive problems that warrant specific diagnoses and therapeutic management. Similar to other states of metabolic stress, T1D represents a challenge to the correct functioning of the reproductive axis.

Nutrition, hormones, and breast cancer: is insulin the missing link?

Breast cancer incidence rates are high in societies with a Western lifestyle characterized by low levels of physical activity, and by an energy-dense diet rich in total and saturated fat and refined carbohydrates. Epidemiologic studies, so far mostly on postmenopausal women, have shown that breast cancer risk is increased in hyperandrogenic women, with decreased levels of plasma sex-hormone binding globulin, and with increased levels of testosterone and of free estrogens. This paper describes the role of hyperinsulinemia as a physiologic link between nutritional lifestyle factors, obesity, and the development of a hyperandrogenic endocrine profile, and reviews evidence that may or may not support the theory that chronic hyperinsulinemia is an underlying cause of breast cancer. An hypothesis is presented, stipulating that breast cancer risk is increased not only in hyperandrogenic postmenopausal women, but also in premenopausal women with mild hyperandrogenism and normal (ovulatory) menstrual cycles. The author suggests further investigation as to whether there is a positive association between risk of breast cancer before menopause and subclinical forms of the polycystic ovary syndrome (PCOS), and to what extent diet and physical activity during childhood, by modulating the degree of insulin resistance during adolescence, may or may not be determinants of a PCO-like hyperandrogenic endocrine profile persisting into adulthood.

A correlation of the outcome of clinical in vitro fertilization with the inositol content and embryotrophic properties of human serum

PURPOSE

This study was designed to investigate whether the level of myo-inositol (MI) in human serum is critical for embryotrophic activity.

METHODS

The embryotrophic properties of human serum were evaluated by the development of postimplantation mouse embryos [in vitro assay of Tam et al. (Fertil Steril 48:834-839, 1987)]. An enzymatic spectrophotometric method using myo-inositol dehydrogenase was used for determination of serum MI. The level of MI detected in serum was compared with the embryotrophic properties and the pregnancy outcome. The effect of MI on the embryotrophic activity of human serum was studied by supplementing the suboptimal serum samples that were unsupportive of embryo growth with extra MI.

RESULTS

Serum obtained from patients having successful IVF pregnancies generally supported better development of postimplantation mouse embryos and contained higher levels of inositol, particularly if the serum sample was collected during the IVF treatment cycle. Serum samples obtained from patients with aborted pregnancies, though supporting mouse embryo development, contained significantly lower concentrations of inositol. An improvement of the embryotrophic properties with exogenous inositol supplement was achieved in some but not all of the suboptimal serum samples studied.

CONCLUSIONS

It is possible that other factors in addition to inositol are crucial in promoting better embryonic development.

The effect of somatostatin analog octreotide (Sandostatin) on luteinizing hormone and ovarian steroids in insulin-dependent diabetic women without residual insulin secretion

In order to determine whether the inhibitory effect of octreotide on luteinizing hormone (LH) secretion and ovarian steroids observed in women with polycystic ovaries (PCO) is a direct or indirect action of the analog, we have investigated the effect of 7 days of octreotide on LH, follicle stimulating hormone (FSH) and ovarian steroids in nine insulin-dependent diabetic women without residual insulin secreting, as in these patients a possibly confusing inhibitory effect of octreotide on endogenous insulin production is excluded. LH and FSH pulsatility over 4 h and hormonal responses (LH, FSH, estradiol, testosterone and androstenedione) to a single subcutaneous injection of buserelin were measured before and after 7 days' treatment with octreotide 100 micrograms subcutaneously twice a day. Octreotide failed to induce a significant reduction in either serum gonadotropin or ovarian steroid levels, although there was a general tendency of hormonal responses to buserelin to be lower with the analog. The effect of octreotide on LH secretion seems to be in correlation with the pretreatment levels which are, in turn, at least determined partly by endogenous insulin secretion. Thus, the results of the present study support the view that insulin has an important influence on LH secretion.