ow-glycemic diets based on the glycemic index (GI) are being recommended for the avoidance and amelioration of the numerous diseases in humans and animals that involve insulin resistance, such as diabetes mellitus type 2 and coronary heart disease in people and some forms of laminitis, exertional rhabdomyolysis, and developmental orthopedic disease in horses. The root hypothesis is that control of postprandial hyperglycemia and hyperinsulinemia will help those who have compromised glucose homeostasis—up to 17% of the human population and all of the horses chronically adapted to sweet feed. This prospect has broken out of the scientific literature, with many books and magazine articles being written for the public. In our opinion, the promise of low-glycemic diets is being emphasized without due regard to current limitations (see Addendum). This commentary aims to clarify salient points and achieve a reasonable balance for current expectations for glycemic dietetics in the horse. GLYCEMIC INDICES