The following observations were obtained: (1) Hypomagnesemia decreases liver COMT activity in non-diabetic mice; (2) empagliflozin elevates plasma Mg2+ levels in diabetic mice; (3) empagliflozin-induced increases in plasma Mg2+ levels result in increased liver COMT activity; (4) in the liver, NE metabolism to NMN is promoted in association with increased liver COMT activity in diabetic mice; (5) NE stimulates IL-6 production in hKCs, which is competitively inhibited by NMN; and (6) empagliflozin reduced IL-6 levels in the liver in diabetic mice. This evidence concerns the gene COMT and familial primary hypomagnesemia.