What is the cause of decreases in male testosterone levels with aging?
The decline in serum testosterone levels with aging in men is quite variable, and changes in health and lifestyle factors can contribute to this variability. For example, obesity and comorbid disease, including diabetes, are associated with greater rates of decline in serum testosterone. In fact, the decline in total testosterone associated with becoming obese (−12%) is comparable to that associated with 10 years of aging among men who are weight stable (−13%). Acute and chronic illness, some medications (e.g., narcotics, glucocorticoids), nutritional deficiency, sleep disorders (e.g., obstructive sleep apnea), stress, and loss of a spouse can also reduce serum testosterone concentrations.