GSTM1 and type 2 diabetes mellitus: However, the risks associated with high Hb targets in recent studies [23, 24] prompted updates to the guidelines to recommend a narrower Hb target: 110–120 g/l and not exceeding 130 g/l for most patients and 100–120 g/l for patients with type 2 diabetes mellitus (T2DM) avoiding levels above 120 g/l, particularly for those at risk of stroke [25].