The PCOS literature has shown for years that high insulin levels from
any source/reason, lowers steroidogenesis and binding globulin that
transports it.  Sex hormones are steroids.

Susan

Testosterone Levels Decrease after Ingestion of Sugar
The results were presented at The Endocrine Society's 91st Annual
Meeting in Washington, D.C., and what they found was that, men with low
testosterone should have their hormone levels retested after they fast
overnight because eating may transiently lower testosterone levels by as
much as 25%, a new study concludes.
"Both the incidence of low testosterone, or hypogonadism, in men and the
annual number of testosterone prescriptions are increasing, likely as a
result of the obesity epidemic and our aging population," said study
co-author Frances Hayes, MD, an endocrinologist at St. Vincent's
University Hospital in Dublin, Ireland, who did the research at
Massachusetts General Hospital, Boston. "The decision to prescribe
testosterone therapy is based on the result of a blood sample, so
obtaining an accurate measurement of testosterone is key to making a
correct diagnosis of hypogonadism."

In current guidelines for evaluating men with hypogonadism, The
Endocrine Society recommends measuring blood levels of testosterone, the
major male sex hormone, on two or more occasions in the morning, when
testosterone is highest. However, no guidelines exist on when to draw a
testosterone sample in relation to food intake, Hayes said.

Past research shows that a high level of insulin, the hormone primarily
secreted after eating, is related to low testosterone levels. Like
eating, glucose intake causes blood glucose (sugar) levels to rise,
which stimulates secretion of insulin. Hayes and her colleagues examined
the impact of a standard dose of glucose on testosterone levels in 74
men. The researchers administered the oral glucose tolerance test, a
screening test for diabetes that involves drinking a sugary solution (75
grams of pure glucose) and then measuring blood sugar levels.

Of the 74 men, 42 had normal glucose tolerance on the test, 23 had
impaired glucose tolerance (also called prediabetes) and 9 had newly
diagnosed Type 2 diabetes.

The authors found that the glucose solution decreased blood levels of
testosterone by as much as 25 percent, regardless of whether the men had
diabetes, prediabetes or normal glucose tolerance.

Two hours after glucose administration, the testosterone level remained
much lower than before the test in 73 of the 74 men, a statistically
significant difference, the authors reported. Of the 66 men who had
normal testosterone levels before the test, 10 (15 percent) became
hypogonadal at one or more time points during the test.

The results did not differ by changes in insulin levels, according to
the abstract. Other hormones that could change testosterone measurements
also did not appear to affect results. Hayes said more research is
needed to find the factor or factors responsible for this drop in
testosterone.

Because glucose intake, and likely food, decreases testosterone, she
said, "This research supports the notion that men found to have low
testosterone levels should be reevaluated in the fasting state."

The Endocrine Society's 91st Annual Meeting in Washington, D.C.