Thursday, September 26, 2013

Low testosterone levels predicted a greater risk of acute myocardial infarction (MI) in Swedish men with type 2 diabetes, researchers found.

Courtesy of medpagetoday.com





 Low testosterone levels predicted a greater risk of acute myocardial infarction (MI) in Swedish men with type 2 diabetes, researchers found.

After adjustment for potential confounders, higher total testosterone levels were associated with a 25% reduced risk of acute MI in that group (HR 0.75, P=0.006), according to Bledar Daka, MD, of the University of Gothenburg in Sweden.

But no such relationship was seen in men without diabetes or in women regardless of diabetes status, Daka reported at the European Association for the Study of Diabetes meeting here.

"In the future, we probably could use serum testosterone for the assessment of cardiovascular risk in men with type 2 diabetes," he said, noting that the findings should be validated in other studies before drawing a definitive conclusion.

Previous studies have revealed a relationship between low testosterone and the development of type 2 diabetes in men, as well as with a greater risk of cardiovascular mortality in otherwise healthy men.
The current analysis used data from 538 men and 571 women 40 and older (mean age 62) who were living in Skara in southwest Sweden and responded to a survey conducted in 1993 to 1994. All had total testosterone and sex hormone-binding globulin (SHBG) measured with radioimmunoassays; free testosterone was calculated using the Vermeulen method.

At baseline, the level of total testosterone was 13.5 mmol/L in men and 1.00 mmol/L in women.

Corresponding levels of free testosterone were 0.26 and 0.014 ng/mL.

The rate of type 2 diabetes was 9.8% in men and 7.3% in women.

Through an average follow-up of 14.1 years, there was a significantly higher rate of acute MI in men versus women among the non-diabetic individuals (14.2% versus 9.7%, P=0.02), but not among those with type 2 diabetes (20.8% versus 24.3%, P=0.45).

Having a serum total testosterone level in the highest quartile was associated a lower rate of acute MI, but only among men with type 2 diabetes (P=0.02). The difference remained significant after adjustment for age, waist-to-hip ratio, smoking, physical activity, LDL cholesterol, and systolic blood pressure. The finding was similar when free testosterone was used.

The test for an interaction between diabetes status and the relationship between testosterone and acute MI achieved only borderline statistical significance, however (P=0.051).

In comments following Daka's presentation, one of the co-chairs of the session, Naveed Sattar, MD, PhD, of the University of Glasgow in Scotland, called the study hypothesis-generating and said that it remains unclear whether testosterone has a direct effect on the risk of acute MI or is simply a marker of risk, even though there are some plausible direct links. Those include testosterone's effects on blood flow and vascular function.

"We're a long way from proving that it's causal," he said in an interview, adding that larger and more comprehensive studies that incorporate genetic information are needed.

"Because if the genes are related, that would suggest it's causal," Sattar said. "And only then should we do some intervention studies, but do them very very carefully."

He noted that a case-control study in the U.K. that includes 10,000 patients with MI and is measuring levels of testosterone and SHBG should be able to provide a definitive answer.

"I think we're kind of early on in the game of testosterone and cardiovascular events in men," Sattar said, "and my gut feeling is it probably won't be the answer."

The study was supported by grants from the Swedish Institute and the FoU VGR. Daka did not make any additional disclosures.

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