Why Hypoglycemia?

A 70 yr-old man was admitted for hypoglycemic attack. So I was asking his wife the history.Me: "Is he on insulin or oral medication?"Pt's wife: "He's on insulin. I'm the one who give him injection coz he can't see."Me: "Then what happened actually?"Pt's wife: "I also dunno la...yesterday he didn't take his dinner coz he said no appetite, then at night after I gave the insulin injection, this