Nicholas Frank, DVM, PhD, Dipl. ACVIM, associate professor of large animal clinical sciences at the University of Tennessee, discussed the causes, clinical signs, and management of insulin resistance in horses, and its link to laminitis at the 2006 AAEP Convention.

"Insulin resistance can be defined as failure of tissues to respond appropriately to insulin," said Frank. "Insulin is secreted by the pancreas to move glucose (sugar from digestion of food) into tissues when it’s readily available (after meals)."

There are three types of insulin resistance.

"Compensated IR is the most common form; this is when the pancreas secretes more insulin to achieve the same effect (hyperinsulinemia)," he explained. "Uncompensated IR is when pancreatic beta cells (the source of insulin) fail, so blood glucose concentrations rise and insulin levels are variable; this is fairly rare. An extremely rare event is Type 2 diabetes mellitus (caused by insufficient production of insulin or by resistance of target tissues to the effects of insulin), which describes advanced pituitary pars intermedia dysfunction (PPID, or Cushing’s). This results in hyperglycemia (high blood sugar) and glucosuria (sugar in the urine)