Abstract
In order to investigate whether glucagon is
implicated in the reduced insulin sensitivity in
hyperandrogenic women, concentrations of glucagon and
insulin in serum were measured during a 75g oral glucose
tolerance test (oGTT) in 24 obese (body mass index, BMI,
>25kgm~2) and 20 non-obese women with polycystic ovary
syndrome (PCO) , and 10 obese and 13 non-obese control
subjects. The oGTT was repeated during alteration of
concentrations of endogenous androgens by administration
of buserelin, spironolactone or a combination of
cyproterone acetate and ethinyl oestradiol to women with
PCO, and by administration of goserelin or danazol to
control subjects. The relationships between glucose,
insulin, C-peptide and glucagon values and those of
testosterone, androstenedione, dehydroepiandrosterone
sulphate and sex hormone binding globulin were examined
before and during treatment. Additionally, the
relationship between basal and glucose-stimulated glucose
concentrations and that of haemoglobin A^ (HbA^) was
examined to assess the value of HbA-^ estimation for
monitoring glycaemic control in women with PCO.
Obese women with PCO had higher serum concentrations
of insulin and glucose than did non-obese women with PCO
and control subjects, but plasma concentrations of
glucagon were greater in obese control women. There were
no significant relationships between fasting
concentrations of insulin or insulin responses to oral
glucose and those of testosterone or androstenedione in
either group of PCO subjects, but the glucagon response to
oral glucose was significantly related to both
testosterone and androstenedione in obese women with PCO.
No significant relationship was demonstrated between
change in serum concentrations of androgens as a result of
treatment and those of insulin or glucagon in any of the
groups. In no case was the HbA^ concentration above
normal laboratory values although a significant
correlation between HbA^ and summed glucose levels was
apparent.
Glucagon does not appear to be implicated in the
insulin resistance exhibited by women with PCO nor do
androgens appear to directly effect concentrations of
insulin or glucagon in normal women or in those with PCO.
Measurement of HbA-t is not sufficiently discriminatory for
identification of impaired glucose tolerance in PCO.
