Normal insulin with high blood sugar.

Looking for information about what normal insulin levels with high blood Sugar and A1c mean. DH had blood test and insulin level was 3.3 with a bs of 288 and A1c of 10! Can't seem to find information anywhere, just high insulin and normal or high bs.
Not on any meds, insists on diet and exercise alone. He does avoid and has eliminated the usual triggers but bs still remains high. This has shocked him into getting aggressive with lowering it now. Any help would be appreciated.