The Food and Drug Administration has determined that two popular diabetes drugs – GlaxoSmithKline’s Avandia and Takeda Pharmaceuticals’ Actos – should carry a “black box” warning about a potentially heightened risk of congestive heart failure associated with the medications. About 11 percent of all African Americans above the age of 20 have diabetes, according to the American Diabetes Association, which advises patients not to stop taking prescription medications without talking to their physicians and to consult their health care providers to discuss their medication’s risks and benefits.