Disclosed are improved compositions and methods for decreasing blood glucagon levels. As disclosed herein, L-glutamine is a selective stimulator of α-cell proliferation generated when glucagon signaling is interrupted. Therefore, disclosed is a method for treating a subject with hyperglucagonemia, e.g., a subject with diabetes, that involves administering to the subject a composition comprising an L-glutamine inhibitor in an amount effective to decrease blood glucagon levels.
