A twelve year study of men in France showed that the combination of low testosterone and metablic syndrome increased mortality. The news article says:
Older men with metabolic syndrome and low levels of total and bioavailable testosterone are more likely to die of any cause over 12 years vs. men without metabolic syndrome, according to findings from a prospective study in France.
Overall, total and bioavailable testosterone were not associated with all-cause mortality in an adjusted model that included metabolic syndrome, according to researchers. However, they observed an interaction between total and bioavailable testosterone and metabolic syndrome on mortality risk (P = .002 and .008, respectively).
In men without metabolic syndrome, researchers did not observe an association between total and bioavailable testosterone and mortality. However, among men with metabolic syndrome, researchers observed a linear trend between testosterone levels and mortality risk. For each 1-standard deviation decrease in total and bioavailable testosterone in men with metabolic syndrome, HR for mortality risk was 1.78 (95% CI, 1.13-2.78) and 1.83 (95% CI, 1.17-2.86), respectively.