Hydrogenated pyrido[4,3-b]indoles, pyrido[3,4-b]indoles and azepino[4,5-b]indoles are described. The compounds may bind to and are antagonists of the adrenergic receptor α2A. The compounds may also bind to and are an antagonist of the adrenergic receptor α2B; or the compounds are not antagonists of the adrenergic receptor α2B and the compounds are administered in conjunction with a second agent that reduces, or is expected to reduce, blood pressure in an individual. The compounds may find use in therapy, e.g., to regulate blood glucose level, increase insulin secretion and treat diseases or conditions that are, or are expected to be, responsive to an increase in insulin production. Use of the compounds to treat type 2 diabetes is particularly described.