Q:  Quick question about insulin. I know that you’re supposed to administer insulin Sub-Q (under the skin), but I have heard that people inject insulin IM (intramuscular) to affect onset times. I am taking Humalog and wanted to increase the reaction time. I have had some wicked episodes of hypoglycemia lately and I want it to kick in almost before I’m done eating. Will IM help?

A: Well, normally I’d say that IM injections would take longer, but in the case of insulin, what happens is, there will be a more rapid onset. That’s because there is more blood supply to muscles and more rapid absorption as a result. But the duration of insulin’s impact will be vastly shortened using that method so take that into account on the backside. I actually recommend doing IM when you first start insulin because it weakens the action and allows your body to get used to it. It is more controlled in that method and decreases blood glucose gradually. I do wonder why you want to decreases the onset time of Humalog since it is one of the fastest acting, but you didn’t say. After you use insulin for awhile, I wouldn’t recommend injecting short-acting insulins IM, just because you can drop the blood glucose too fast and cause problems in the brain due to increased osmolality of the blood.