Major BG spike 4 hours after dinner

Help! I am having a major BG spike 4 hours after dinner. The meal is the usual. Not high carb/protein/blah blah. For 4 hours I go smoothly sideways after the meal bolus (or even lowish so I turn off basal for a little while) and then zip up 100 to 150 pts higher right as I am going to bed or worse an hour after I am asleep. Are my carefully crafted basal settings that have worked for months just suddenly wrong? Is turning off insulin for the after dinner low causing a delayed spike? Or???

Too much missing information. Why would you be turning off basal after a meal? Are you over-bolusing? If you are using a Tandem with CIQ, then I would suggest that you use the extended bolus and NOT turn anything off after a meal. The extended bolus goes for only 2 hours (or you can set it for as short a time as you wish), and CIQ will take over after the 2 hours. Also, eat at least 4 hours before going to bed. If you are not on the T-slim with CIQ, then I don’t know, but I think that turning basal off after a meal is not a good practice with any pump.

No Tandem. Just a simple Omnipod and Dexcom. I shut down insulin via pump after dinner because I am going low for about an hour after eating/blousing. When I spike hours later I still have IOB (so I am not under blousing for the meal).

And I bolus only about 15 minutes before the meal. Not way ahead of time

If this is happening consistently, maybe try an extended bolus with the Pod instead of reducing your basal?

I would suggest taking your bolus right when you start eating because it’s hitting you sooner than you want.

If you are not eating a high fat meal the extended bolus might help you.

I’ve never had this, but what you describe could be gastroparesis. Where your stomach doesn’t empty predictably.

It’s something diabetics get sometimes. What is your a1c running?

When did you change your insulin site? I have a different absorption rate whenever I change my site. Only thing I can think of if it goes that high that quickly.

Gastroparesis. I’ve heard of it. My A1c was 5.7 last check. Last night I was at 91 all night after a POD change. I will keep an eye on gastroparesis symptoms. Thank you for the help

After changing a POD my numbers overnight were perfect. Thanks for the help

5.7 is pretty low. Would be hard to tighten up control better than that although there are several people on this site who pull it down to the 4s.

Just what I would do, increase basal to stop spike, do activity. You may be hungry again or need a snack. My bg goes up just from that.

My daughter (age 11 T1D) has often had blood sugar spikes as she’s getting ready to go to sleep at night or the first hour or two after she falls asleep. It was perplexing because it kept happening seemingly regardless of what she ate for dinner or when. My theory is that it’s hormonal, specifically growth hormone that’s release during that time of night that causes her to become more insulin resistant for a few hours, almost every night. Adults also secrete growth hormones as part of healthy bodily functioning. We have tried anticipating it and just pre-blousing for bedtime and/or correcting more aggressively at that time. Hope that helps, no one seems to talk that much about hormone shifts as a bedtime factor.


If this is suddenly happening consistently, where it hasn’t been the case in the past, and you want to know the cause you should see an expert, first your PCP, then an endocrinologist in a practice with diabetes educators who are current with the latest tech.

This is a forum of folks who have learned or are learning to live with “manage” our symptoms of diabetes. We each have some expertise in what works for us individually, but are not medical experts. Each has different insight because of our backgrounds. I’m an oddball. Mine is general engineering.

Regardless of the cause(s), what is happening is clear if one pragmatically understands how infused insulin is supposed to work.

The goal of a bolus is to metabolise a specified amount of ingested glucose within a fixed amount of time. Bolus insulin that is infused has a “working duration” of approximately 4 hours. That’s how long it takes for +95% of it to get into the bloodstream. (Approximately 75% gets in within 3 hours. )

The time delay in a post-meal BG spike means that all your bolus insulin has been assimilated before the part of the meal that could be digested to a glucose form has been. Four hours after your bolus, you don’t have enough IOB Insulin On Board to finish the job.

Here’s an analogy.

Imagine you were in a car on a road with an enforced maximum speed limit of 55 mph. That car has a bad battery and must keep burning some gas to stay running, whether it’s sitting still or moving. Your goal is to get somewhere 200 miles away within 4 hours of leaving, to drive/“eat up” 50 miles each hour.

“No problem”, you think.You “bolus” the car with gas for the trip, adding just enough gas to get 200 miles - assuming you drive at an average of 50 mph.

Here’s the problem. If the traffic is heavy you’d need to slow down. If you drive slower than 50 mph, you can’t reach the goal in time. The speed gauge (BG) would drop. Your gas gauge would drop (insulin level). Either you wouldn’t have enough gas, or not enough time. You couldn’t achieve your goal.

Heavy traffic is like impeded digestion. It doesn’t matter whether it’s from a flat tire, construction, too many cars on the road, a collision, a gaper’s bloc, or news flash that something bad has happened. It’s effect is the same. The traffic/food isn’t flowing down the road uniformly or fast enough and causing delays.

This is an imperfect analogy because insulin is more like a catalyst than a fuel, but the principle is the same. Your body, especially the brain, needs some insulin all the time. Infused insulin has a working duration of a few hours, and you need more when you eat.

If you go low for an hour after bolusing for a meal, whether it’s consistent or not, then you are infusing insulin too far in advance of your body’s digesting the food.

The short term solutions are reactive and proactive.

  • Reactively, you correct. You “add more gas” to get where you want to be, slower.
  • Proactively, you delay the bolus. You leave later and avoid the traffic delay. stressed out drivers,
  • In no case do you stop basal delivery, the “gas” that your body needs to keep running.

A bolus during impeded digestion can be simply delayed, extended as a square wave of time, or combination of both.

I have chronically impeded digestion and have tried all the variations depending on the meal composition and my health that day. Thankfully, I now have the luxury of a time and situation where this is feasible.

For me, delaying a single bolus is the least effective. Splitting my bolus between 50% delayed, and 50% extended over a period starting when I see my CGM start to rise works the best. But doing this requires more attention than the result warrants. Instead, I focus on keeping my overall TIR consistent by monthly tweaking my time profile - basal rates, meal ICRs based on a month’s results.