Boston Testosterone Partners

The aim of this study was to examine whether long-term testosterone replacement therapy could help improve risk factors for heart disease and reduce narrowing of the arteries in men with low testosterone levels who also had metabolic syndrome and/or type 2 diabetes.

For the first 12 months of the study, men received either an injection of testosterone undecanoate into muscle every 12 weeks, or a dummy drug (placebo). Delivering this form of testosterone into muscle means that testosterone levels are stably released from the depot in the muscle and maintained within the normal range without the need to take testosterone daily. Because there was such an improvement in risk factors during treatment with the testosterone replacement therapy, all of the men were given testosterone therapy for the rest of the 24-month study.

Key Findings

  • The testosterone replacement therapy, but not the placebo treatment, improved a number of important indicators that can provide warning of heart disease and narrowing of the arteries (atherosclerosis)
  • In particular, testosterone reduced waist circumference, reduced the amount of visceral fat, and improved the body’s sensitivity to insulin
  • Testosterone therapy also reduced signs of inflammation and artery disease related to thickening of the artery walls
  • By the end of the study, i.e. after two years of treatment, more than a third of men no longer had signs or symptoms of metabolic syndrome.

Source: Effects of testosterone undecanoate on cardiovascular risk factors and atherosclerosis in middle-aged men with late-onset hypogonadism and metabolic syndrome: results from a 24-month, randomized, double-blind, placebo-controlled study. Aversa A, Bruzziches R, Francomano D, et al. J Sex Med 2010;7(10):3495-3503.

 Background information

 Late-onset hypogonadism refers to the progressive decline in serum testosterone related to advancing age and characterized by a deficiency in serum testosterone levels below young healthy adult male levels.

Metabolic syndrome is a group of conditions linked to being overweight or obese: three or more of these conditions together is sufficient for a diagnosis of metabolic syndrome. These conditions or characteristics are:

  • A large waistline (which is linked to insulin resistance)
  • A higher than normal fat level in the blood – in particular raised levels of triglycerides
  • A lower than normal level of ‘good’ high-density lipoprotein (HDL) cholesterol in the blood
  • Higher than normal blood pressure
  • Higher than normal blood sugar levels.

People with metabolic syndrome are at greater risk of heart disease and diabetes.

Visceral fat is the hard-to-lose fat around the internal organs that makes people more susceptible to heart disease, stroke, diabetes and high blood pressure.

Insulin resistance is a condition that makes it harder for the cells of the body to use insulin effectively to process sugars and fats. If insulin resistance is present, as in metabolic syndrome, the normal response to insulin is reduced and more insulin needs to be secreted. Insulin resistance can precede the development of type 2 diabetes.

Atherosclerosis is the process in which fatty deposits build up in the inner lining of arteries, narrowing them and increasing the risk of heart disease and stroke. Reducing the narrowing and inflammation that are a part of atherosclerosis is a sign a treatment is beneficial in slowing the progression of atherosclerosis.

This is the first such study to show that long-term testosterone replacement therapy with a long-acting testosterone injection can improve body composition, insulin resistance and atherosclerosis in men with low testosterone and metabolic syndrome. This raises the possibility that testosterone replacement therapy may have an important role in delaying the progress of metabolic syndrome to heart disease.