Recent evidence strongly suggests that testosterone deficiency is a predisposing factor for various chronic illnesses, including cardiovascular disease, diabetes and osteoporosis.[1-3]Testosterone deficiency has also been implicated as a modifiable disease risk factor for various chronic diseases in otherwise well patients.[4-7]
Cardiovascular disease, diabetes and osteoporosis-related fractures consume a significant portion of the $2.3 trillion in annual U.S. health expenditures. The economic impact of diabetes is estimated at $503 billion, $152 billion for cardiovascular disease, and $6 billion for osteoporosis-related fractures.[8-10]
Thus, the total burden of these diseases is over $660 billion, representing approximately 29% of all U.S. health care expenditures in 2008. Since testosterone deficiency is a potentially modifiable risk factor for these and other medical conditions, it may be responsible for substantial financial and quality-of-life burden on the U.S. health care system.
A study was conducted to specifically quantify the cost burden imposed by consequences of testosterone deficiency ...
The consequences of low testosterone levels (aka low-T) have been primarily investigated in middle-age and older men. However, low-T in young men aged 20-39 years can confer health risks as well...
Low total testosterone levels are associated with an adverse blood lipid profile, which includes high TG and low HDL, [1, 2] and a decline in total testosterone levels predisposes men to increased risk of cardiovascular disease (CVD) and mortality.[3-7]
It is well-documented that testosterone levels decline with age in men.
After the age of 40 years, total testosterone decreases on average -4 ng/dL ( -0.124 nmol/L) per year  or 1.6% per year , and bioavailable testosterone by -2 to 3% per year. 
In older men (over 60 years of age), the average rate of decrement in total testosterone levels has been found to be 110 ng/dL every decade.
However, the relative contributions of changes in health and lifestyle to that decline have not been adequately evaluated. A notable study was set out to investigate this...
The objective of this study was to establish the relative importance of aging, health, and lifestyle in contributing to the testosterone decline in aging men.