Insulin is not responsible for acidity. I feel your husband has type 2 Diabetes and if so he may be safely switched over to oral diabetic medications. The decision of which drug depends upon his weight and associated conditions like high BP, high cholesterol etc. In fact most of the type 2 DM patients who are started initially on insulin due to various reasons can be safely shifted to oral medications. On occasions only diet and exercise are good enough to control blood sugars for variable length of time. Please consult your physician / diabetologist.