Advice please for post meal test timing

Hi. I had a chance to try the FreeStyle Libre and noticed high spikes after breakfast. I’m trying level those off, but no longer have the benefit of a sensor, so am testing with a finger prick.

I bolus at about 7: 30 am and start eating at 8. What is the best time to test so that I am getting a reading when the blood sugar level would peak? I realize that this is a very subjective question, but I’m trying to limit the amount of finger pricks in order to fine tune this measurement. I’ve read that one should test 2 hours after a meal, but because I’m delaying eating, should that be 2 hours after I bolus or 2 hours after I start eating?

My blood sugar does level out by lunch time, so figure that pre-bolusing is a good place to start.

I know that if I ask my diabetes team, they will probably say that high 10’s (mmol - so approaching 200mg/dl) or low 11’s are ok as long as I’m ok by lunch time. I however, would like to improve on this. And at this point, I’m not willing to give up my oatmeal. My typical breakfast is 0% plain Greek yogurt with blueberries and quick oats with fruit, usually apples and hemp seeds. I aim for about 30 grams of carbs. Would steel cut oats be better? I’ve been trying to stay away from bananas, but 8-10g CHO from a banana doesn’t seem to make a big difference.

Any advice would be welcomed and appreciated! Thank you.

When I do this without a sensor, I test once an hour (before breakfast until lunch if thats your interval of interest). But, frankly, it sounds like inadequate basal, not a meal bolus issue. Data will help us trouble shoot this. I agree that a 200 post meal BG isn’t way off target. But, after two hours (approximately) it should be normal again if the basal/bolus are correct… Have you tried increasing your bolus? What happens if you dont eat breakfast? Thats important to know.

Couple of thoughts. My guess is that you’d want to measure the 2 hours from when you eat, not when you bolus for it. You’re trying to catch the post-prandial peak under normal circumstances, which assume pre-bolusing by half an hour. Obviously the 2-hour thing is more of a rule-of-thumb than an absolute, so you probably need to do a sequence of tests to isolate the top of the rise. High fat and protein content in your meal can also delay things considerably, so if you are having bacon and eggs it wouldn’t hurt to spread your first try at this over several hours, but it sounds like that’s not an issue.

Also: what @mohe0001 says.

I always thought that BG peaked one hour after first bite and was to be down to baseline at the two hour mark. However, BG has never been down to baseline after two hours for me. And quick oats and apples are the devil’s concoction for my BGs. Steel cut oats are supposed to be better but I find them to be pretty much the same. It may be portion size in my case.

If I were in your situation, the first thing I would try to discover is the optimal pre-bolus time for you. I see utilizing an appropriate pre-bolus time as a powerful tool too often unexploited by people with diabetes. There are only two insulin dosing factors within your control: dose size and dose timing.

An optimal pre-bolus time varies from person to person but also varies in the same person from meal to meal and day to day. I would fingerstick check your glucose at the time that you dose your meal insulin and then check about every 15 minutes until you see a distinct downward glucose trend. When your glucose is in-range and dropping, that is the ideal time to eat from a post-meal control perspective.

I know you are trying to minimize fingersticks but knowing your nominal and optimal pre-bolus time will help a lot with post-prandial numbers. My optimal pre-bolus times vary from 15-60 minutes and it tends to be longer in the morning when my insulin resistance is relatively higher.

Once you use a known good pre-bolus time, I would test at first bite and then at 1 and 2 hours later.

I too loved my oatmeal so understand your attraction. I found, however, that I could not control my post meal numbers, especially in the morning, if I ate oatmeal. I’ve since given it up and often eat eggs with breakfast meat as well as chia pudding, a nice oatmeal alternative.

If memory serves me, I recall that 1/4 cup of dried oats measures in at 27 carbs. If you add blueberries and apples, you may be pushing 45 or 50 grams of carbs. I know people can successfully dose for higher carb meals but I choose to not do that. I just find it easier and more dependable to eat lower carbs.

You might be interested in reading Adam Brown’s Bright Spots and Landmines, a great resource to help with the issues you’ve raised in your post. Adam recommends limiting carbs to about 30 grams/meal.

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A few things…

Less carbs for breakfast. Many diabetics have issues with oatmeal. Adding dairy and fruit only increases the carbs, probably more than you think they are.

Pre-bolusing as Terry4 mentioned is a great tool. It’s better and easier to prevent a high than to chase a high.

Insulin resistance. Many diabetics are more insulin resistant, often in the mornings but this varies from person to person. I simply need more insulin to cover breakfast than I do for the rest of the day.

Test 2 hours after you finish eating your meal and test 3 hours later as well. Depending on the meal composition (protein, carbs & type of carbs, fat) you will likely see differing results in your BGs post meal. Depending on what I’ve eaten and bolused for I might be in range 2 hours post meal but dipping low at 3-4 hours so I don’t get too worked up if I am still slightly above my target 2 hours after a meal if I am routinely at my target 3 hours later.


Thanks for all the input and some “food for thought”. :wink:

Some facts: I am only eating 30g of carbs for my meals. CHO make up is 3.5 for frozen blueberries, 3.5 for non-fat greek yogurt, 14 for quick oats, and 9 for low-glycemic fruit.

Insulin sensitivity is a problem in the morning. Basals:

12 am - 6 am: 0.5
6 am - 10 am: 0.85
10 am - 12 pm: 0.65
12 pm - 6 pm: 0.225
6 pm - 12 am: 0.55

Exercise: treadmill for 25 min. starting about 10:15 which requires the lower afternoon basal.

I first tried a 15 min. delay and now doing 30. I see that @Terry4 might delay up to an hour. When I had the Libre, I did check for a downward trend before eating breakfast if my bs was high, so maybe that’s what I should be doing now in order to pin down the proper delay time.

I think I do have Adam Brown’s book on my reading list. I have enjoyed some of his articles.

Thanks again all!

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I ate 30 carbs a day for 11 yrs. 2 1/2 yrs ago I switched to low fat plant based. Every morning I eat 1/4 of a cup of cooked oat grouts with a bit of flax and chai seeds. On top of that I have one cut up banana, 1 cup of blueberries, and one cut up large date. I don’t use milk. I usually eat about 300 carbs a day and take 23 total units of insulin. I am happy with a reading of 140 two hours after eating but am often back down to 100 two hrs after eating.

I was dx in 1959 and have no diabetic complications.

I commend you. I used to eat 200 carbs a day 'cause that’s what “they” told me to do. I think I’m much better off now at around 100. Over the past year I have gradually moved to a whole food, more plant based diet. It also really helped improve my eating habits by getting rid of my husband and being able to control what food was in the house! :wink:

Dx 1992 with no complications.

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It’s different every day and breakfast is the most difficult and variable meal in my experience. The quality of sleep the night before can make a huge difference, along with a million other variables. I’ve seen huge spikes eating only 5-10g of carbs some days, and other days didn’t see this eating more grams. The best way I’ve been able to avoid spikes is eating low to no carb breakfasts (eggs and cheese for example) and bolusing for the protein using an extended bolus or Regular insulin. Otherwise a CGM or Libre is your best friend if you are able to get one again. The spikes can happen very quickly, sometimes it might be 2 hours but others days could happen as quickly as 10-15 min after eating. You can go by how you feel too, I find if I am spiking fast in the morning I will feel it, but everyone is different of course.

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Bananas. hmm. I will eat a part of a banana if I want to raise my bg’s. I’m surprised it doesn’t increase your bg’s.

I eat a whole banana, 1 cup of blueberries, a date and oat groats every single morning. I also eat part of a banana if I need to raise my blood sugar at another time during the day.

Dave - My guess is that anyone that thinks that a whole banana does not wildly increase their BG and harm them is not on a CGM and without real time information is guessing that their BG is under control due to their long term A1C being where they like it.

Well let’s see CJ114. I have been a type 1 for 60 yrs. I definitely know what I am doing. I have no diabetic complications. I am 68. I started getting retinopathy when I was 30, so I cleaned up my act and got my very first glucose monitor. I have not had an A1c over 5.6 in 20 yrs. I definitely know what I am doing!

I finished eating my whole banana, 1/4 cup of oat groats, 1 cup of blueberries, and large date at 7:30. I gave myself 5 units of Novolog before breakfast because I wasn’t going to the gym this morning. When I go to the gym I give 3 units before I eat my breakfast. At 9:30 my glucose level was 120. I don’t have a GMC but I am one of the best controlled type 1 diabetics you will ever hear of and I am quite proud of it.

I usually take 19 to 20 units of total insulin daily and eat about 275 carbs daily. I make none of my own insulin. I eat a plant diet with very low fat. I also exercise.


So happy to hear you are in total control of your life and diabetes management. Although my stats are perfect or near perfect all the time, my diet is not as varied as I would like it to be and have been working toward more plant based and more carbs. So far, however, have not been successful without increasing insulin. My body makes plenty of insulin, just can’t process it. Keeping a low A1C is not an issue, keeping a low standard deviation is more of a challenge as soon as carbs are increased. I keep BG between 60 and 150 during day and 60 and 130 at night and can go 30 days 24/7 never getting out of that range on low carb. As soon as carbs are increased, start getting the odd BG reading out of that range.

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The secret to becoming plant based is the low fat. I only eat 15% fat. I ate 30 carbs for 11 yrs. The low carb diet was very harmful to my body, and I only wish I had understood that sooner. We are all different.

On the low carb diet I took 17 units of insulin daily. Now I am averaging about 22 units. The hour I spend exercising helps keep my units low. Some of the days last week I only needed 19 units of insulin for the same amount of food. I hate counting carbs and I love the food I eat, so I will eat the same foods day after day. Then I will try a new recipe and eat that for a few days.

When I was eating the SAD (Standard American Diet) I took about 40 units of insulin to keep my glucose levels reasonable.

I try my best to keep my levels close to what you are doing, but don’t worry as long as I am back down to 140 within two hours after eating. I do much better if my glucose level isn’t higher than 70-90 before breakfast. Lately my glucose levels never go over 90 at night and are often 60 when I wake up at 6:00am. If I sleep another hour they will rise. I used to have to give a unit or two in the early morning hours, but I raised my Tresiba by a unit and now my morning readings are very good. I am fortunate that I always wake up if my levels fall too much at night.

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I am on a CGM and a banana isn’t that bad. (same with blueberries) But I am usually eating it as a snack towards night when I am more insulin sensitive, but I don’t even bother to prebolus for a banana. (unless I’m high to start) A banana is about 25 carbs and I take about 2-4 units after I’ve eaten one. I’m usually not eating any full meals after 6 pm. I don’t hardly ever go above 140 from it.

But for higher carbs, generally prebolusing is the best way to keep it under 150. I take what I think are going to be my carbs and back off some of the guess in case I don’t eat it all. Then I prebolus half of it a half hour before and the other half 30 minutes later when I plan to eat. Then if I’ve eaten more or want something else I will do a “make up” bolus. I will be at my highest 1-2 hours after I eat. Sometimes it will not ever go above 130 using this method.

Of course if it’s a high fat meal, it’s totally a different game. But most of my meals aren’t high fat, I do eat avocado and nuts, but I am a vegan.

Lol, and then there are the times I forget to take a prebolus and something is ready to eat and I will go higher then, although still usually not above 180. If I am eating above 45 carbs I really try to make sure I prebolus.

My settings are 70-170 and I generally stay in that range about 92% of the time. Invariably half my peaks are in the dawn hours from my dawn phenomenon that has started earlier than my meter is prepared for. Plus I don’t eat or eat very low carb in the am as I am insulin resistant in the mornings following my dawn phenomenon until about 10 or 11 am. If my BG’s didn’t go up at dawn they will after I get up, so skipping eating has been the easiest way to control it.

Do you think your heart disease and subsequent stent treatment was caused by the low carb high fat way of eating? Is heart disease unknown in the low fat high carb plant based eating community?

Hi Terry, I think that having an LDL reading of almost 300 which I got while low carbing definitely helped cause my heart disease. Most folks with heart disease end up on the diet I am on now. An example of this would be Bill Clinton. It is the best diet one can be on to prevent heart disease. There are tons of studies which say this.

I imagine that having a grandfather who died in his 60’s from a heart attack didn’t help either. I also had migraines and extremely low blood pressure that caused me to pass out after years of low carbing. For the past 2 1/2 yrs I haven’t had a bad headache nor have I passed out.

I think low carbing is a great diet for diabetics as long as their LDL levels don’t rise. My HDL and Trig levels were great, and my A1c was 4.7 but with an almost 300 LDL level, I ended up needing stents.

Hmmmm, the more I follow this, the more I realize it appears to mostly depend on the individuals I:C ratio. Marilyn6’s I:C appears to be about 1:14 (275 carbs for 19 units). Marie20’s I:C appears to be about 1:8 (Rounding 3 units for 25 carbs. My I:C is 1:3. Additionally, tight control also does not appear to be as important to some as it is to others. Many appear nonchalant about going out of range as long as it is for a “short” period of time and as long as they are back to their normal a couple of hours after eating. I certainly thought that way before going onto CGM as my A1C’s have always been great. Once on CGM, my entire eating, dosing and exercise regime changed, not to improve A1C but to stop all hypoglycemic and hyperglycemic events as well as dramatic reduction in insulin requirements. My last 30 day Dexcom clarity (24/7) report was showing not 1 hypoglycemic/hyperglycemic event in past 30 days and I was totally off of any medication including oral meds and insulin. During those 30 days, my 2 pieces of hardware were my digital scale to view weight and my Dexcom CGM for BG. I did not look at the % or amount of protein I am eating, just made sure carbs were low and not to exceed 24 per day. Also did not exercise as did not want to add another variable into my test.

Is what I am doing sustainable? Most likely not, but it gives me a baseline to start from and keep very low standard deviation and very high TIR. My TIR was 97% for 90 day periods before starting this madness. 100% for last 30 day report blew my mind but now see it is actually feasible.

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