Metolazone

Is there any chance that Metolazone could possibly effect or have an interaction with high dosage uses of insulin? My husband is a severe diabetic and is taking 65 units of Lantus every evening and 20 units of Humalog at each meal. Since starting the Metolazone therapy, we are unable to attain a blood glucose level lower than 280. Mostly runs 300-400. Thank you

Jan Raderstorf