What does it mean to have insulin resistance? My aunt wants to know.

Obesity. There are 2 mechanisms of diabetes: insufficient Insulin or Insulin that isn't working. When the latter occurs, Insulin resistance is the usual cause. Obesity is the most important factor behind Insulin resistance. Most patients with type 2 dm actually produce more than average Insulin but the Insulin isn't able to act properly.
Abnormal Metabolism. Insulin resistance (ir) is a progressive deterioration of glucose and lipoprotein metabolism resulting in increased cardiovascular risk. Abnormal lipoprotein levels, high Insulin and high glucose levels are seen over time. Early on a combination of increased large vldl and small LDL particle numbers, and decreased large HDL particle number occurs and can predate high glucose by a decade.