Does it take insulin more than 2 hrs to work? dads bs was 500 he took 6 units of insulin and 2 hr after it was 493

Depend: Depends upon the type of insulin. Fast-acting Insulin (novolog, humalog, (insulin lispro) apidra) start to work in just minutes. Regular doesn't work for several hours. Other insulins take many hours to begin to work and don't lower blood sugar acutely. If glucose was 600, it'll take more than 6 units to lower it. Will also need lots of fluids to reverse dehydration. Contact his doctor asap.