I was told that calcium blockers are ineffective against diabetes in african americans. is this true?

Calcium channel meds: Calcium channel blockers,used mostly for HTN, work well in Afro Americans. B blockers not as effective for HTN in Afro-Americans, ACE-I and ARBs should be used with a diuretic in Afro-Americans. Calcium channel blockers may decrease destruction of B cells in diabetics with HTN, though ironically some studies show the incidence of diabetes increases in HTNs on calcium blockers.Discuss w/doc