This study found that maintaining testosterone levels above 550ng actually reduced cardiac disease risk. Note that they tested estradiol levels, which was lacking in the inaccurate study recently published. In addition, they found negative correlation between testosterone levels are type 2 diabetes risk. This study was done over 5 years and analyzed all kinds of markers, including SHBG.
High Serum Testosterone Is Associated with Reduced Risk of Cardiovascular Events in Elderly Men