NEW YORK — Men with Type 2 diabetes who have low testosterone levels can benefit significantly from testosterone treatment, says a new study led by Dr. Paresh Dandona.
"This is the first definitive evidence that testosterone is an insulin sensitive and hence a metabolic hormone," said senior author Dandona from the University at Buffalo.
The UB researchers found that low testosterone levels were associated with significantly decreased insulin sensitivity.
This was demonstrated by a 36 percent decrease in the rate at which glucose is taken up by tissues when patients with low testosterone were administered a set concentration of insulin.
"We hypothesized that testosterone may be an anti-inflammatory and insulin sensitizing agent, since it has been known for some time that testosterone reduces adiposity and increases skeletal muscle," he said.
The current study included 94 men with Type 2 diabetes. Prior to being treated, the 44 men in the study with low testosterone levels expressed significantly lower levels of insulin-signaling genes and, thus, diminished insulin sensitivity.
These men were randomized to receive a testosterone injection or a placebo every week for 24 weeks.
The study found that while there was no change in body weight, testosterone treatment produced a reduction in total body fat of three kgs while increasing muscle mass by the same amount.
"Most importantly, we saw a dramatic increase in insulin sensitivity, demonstrated by a 32 percent increase in the uptake of glucose by tissues in response to insulin," Dandona said.
At the same time, there was a similar increase in the expression of the major genes that mediate insulin signaling.
The study was published online in the journal Diabetes Care.