They found that these agents appeared more effective in addressing the cardiovascular manifestations of pheochromocytoma. Colwell indicated that tumor removal was more effective than phentolamine, an alpha-blocker, for restoring normal glucose and insulin homeostasis and suggested that effects on insulin secretion may not be mediated entirely through α-adrenergic receptor stimulation [25]. Here, INS is linked to hereditary pheochromocytoma-paraganglioma.