By Perky Latest Reply 2008-12-24 12:27:15 -0600
Started 2008-12-16 13:04:46 -0600

When testing after eating. I was told to wait 2-hours. How much long can you wait to test after the 2-hours before it would be considered before eating. And also when drinking something how long should someone wait to test.

5 replies

Toma 2008-12-24 12:27:15 -0600 Report

Hi Perky,

KD is right on. We as diabetics are in a way lucky to be able to see results immediately. Most foods will start showing an effect on our blood glucose either positive or negative within 15 minutes. Most foods will peak between an hour and two hours. There are some notable exceptions. There is the pizza effect where food with a lot of fat will be slower to raise the blood glucose and peak later as well as show increased blood glucose readings for a longer time. There are some foods that actually reduce blood glucose readings. If we start understanding generally how foods are supposed to work we can then further refine how that specific food works for us. We can be our own lab rats and run our own experiments.

I have a routine I use for evaluating a new food I am thinking about adding to my diet. I will take a reading prior to eating the new food. This reading is at least 4 hours after a previous meal so I am isolating it from the food I am testing. I then prepare a 100 gram (3.5274 ounces) portion of the food I want to know about so it has a known weight and I am comparing apples to apples so to speak. The standard portions for Glycemic Index testing are sometimes either higher or lower than this and I have not figured out why the portion test sizes are not all standardized. Reviewing the GI database at www.glycemicindex.com can give you a pretty good idea of what to expect from a lot of foods.

After eating this isolated food I will test at 15 minutes, 30 minutes, 1 hour, 2 hours, 3 hours and 4 hours. This gives me the data I need for evaluating that particular food. I wish I had a continuous monitor to be able to see the full curve but I do not. Those are usually only available to type 1 diabetics on a pump and they are very expensive.

The methods used by Sydney University GI Research Service (SUGiRS) is as follows (some other labs use slightly different test portions and methods but pretty close.) The GI value of a food is determined by feeding 10 or more healthy people a portion of the food containing 50 grams of digestible (available) carbohydrate and then measuring the effect on their blood glucose levels over the next two hours. For each person, the area under their two-hour blood glucose response (glucose AUC) for this food is then measured. On another occasion, the same 10 people consume an equal-carbohydrate portion of glucose sugar (the reference food) and their two-hour blood glucose response is also measured. A GI value for the test food is then calculated for each person by dividing their glucose AUC for the test food by their glucose AUC for the reference food. The final GI value for the test food is the average GI value for the 10 people.)

When to test and how often will depend on where you are in the learning curve. When newly diagnosed my testing schedule was 8 times a day. That was when I woke up, (fasting blood glucose) two hours after breakfast and then before each snack or meal and at bed time. After a few weeks that was reduced to 4 times a day and eventually just once a week. (unless you are testing more to evaluate a particular food) When you have a pretty good idea of how you are doing and you have the blood glucose well controlled with a good idea of what to expect and you are just doing what I call maintenance testing you may only need to test once a week to verify that you are still well controlled.


kdroberts 2008-12-17 15:08:41 -0600 Report

The two hours is kind of a guide, and not always a very helpful one in my opinion.

My philosophy is experiment for a while. Take your blood sugar 1, 2 and 3 hours after you start eating for as long as you can but about a week if possible. Then figure out which time you are getting your highest readings and then only test at that time. That way you will know how different food effects your blood sugar. If the spike is too high then you either eliminate that particular food or experiment with different portion sizes and different preparations.

It's pointless to just test after 2 hours if it doesn't tell you anything and/or if you don't do anything with the result.

jaclyncrystal 2008-12-17 15:39:35 -0600 Report

agree with everything kd said, that is how I feel as well, my bs are usually higher around lunch time so, I found that I need some exercise after breakfast and before lunch that seems to even things out. jackie

Anonymous 2008-12-16 13:20:47 -0600 Report

Personally if I miss the 2 hour after I just wait till before I eat again. And are you talking about drinking alcohol?. I only drink 1/2 glass of red wine after dinner at night to help with morning highs. Maybe someone else can tell you about the drinking.

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