Diabetes India

When to test the PPBS; after 90, 110 or 120 minutes of a meal?

When to test the PPBS; after 90, 110 or 120 minutes of a meal?

"When to test the PPBS; after 90, 110 or 120 minutes of a meal" is a question asked by numerous diabetic patients in HealthUnlocked as well as outside. Patients & many labs follow timing of their choice AND EXPECT A VALUE BELOW 140 mg/dl IN ALL CASES. :-)

I feel, the timing depends on the purpose & state of mind of patient &/or doctor &/or lab.

Purposes can be:

1. If it is to cover up the diet/medication violations & to console oneself or convince the doctor that the patient is following the instructions meticulously and results are fine, test PPBS as late as possible - say after 150 minutes (two & a half hours) or so of completion of food intake.

2. If it is to find out how the Pancreas is working & what is the nearly steady state value, test PPBS at exactly 120 minutes (two hours) of completion of food intake.

3. If it is to find out the peak value of blood sugar following a meal, test PPBS before 90 minutes (one & a half hours) of completion of food intake. Higher the Glycaemic Index (GI) of the food, earlier/faster occurs the peak. In the case of Glucose intake in OGTT, peak occur-res between 30 & 60 minutes (almost at 45 minutes).

Even though blood sugar escalation with food intake and Glucose intake for OGTT are different, following it in the latter case gives a repeatable, comparable & standardised pattern. Please imagine the lines joining test values of the SAME OGTT of the author. Test after 120 minutes will miss LOTS OF HIGHER VALUES. Test at 120 minutes will miss lesser number of HIGH values. Test before 120 minutes will miss only still lesser number of HIGHER values.

Wikipedia on Postprandial_glucose_test ( en.wikipedia.org/wiki/Postp... ) says: "For a 2-hour postprandial test, a meal is eaten exactly 2 hours before the blood sample is taken." It is EATEN and NOT began eating.

In a home OGTT (Glucometer) after consuming 75 gm of Glucose (on completion of three years of normal rice based diet thrice daily & occasionally sweets & coffee/tea with sugar), following are the blood sugar values & timings:

Time | BS


----- | ------

00.0 | 096

30.0 | 199

45.0 | 217

60.0 | 210

90.0 | 195

120.0 | 125

Pictorial/graphical representation of these results are given on top for better appreciation. In this case time gap between first bite & completion of food intake is less than a minute & obviously GI is the highest.

This exercise is done because such a sequence of Blood Sugar test is not seen by me anywhere else. Valuable comments of all readers/members are earnestly solicited.

11 Replies

Counting the time from the first bite of a meal makes sense since the BG starts increasing from the first bite .If a person takes about 30 mts for completing food intake ,his BG would have already reached a value close to the peak by the time he or she completes the food intake. .So also for a person taking 15 mts for a meal .For a standard OGTT test the difference between the start and finish time of the meal will be only a few seconds and therefore it is immaterial .But for a meal such as B/F or lunch ,I think the time counting should start from the first bite if we need to capture the true BG .

1 like

Normally in diabetics BS reaches its peak within 60 to 75 min. from start of a meal. If it is measured 70 min. after finishing of a meal then peak reading would be missed. In my case I measure at 70min from start of a meal ( I have confirmed that my peaks are around 70min. by taking BS readings at different intervals.) . If I add 20min. for my lunch then I have to measure around 90min. mark as mentioned here. If I measure at that point then I would miss my peak value. Within 20 min. drop could be in the range of 10 -20 mg. (For most of the diabetics after 120min. the drop in BS is very slow. So there is not much difference at140min reading.)




I think even ADA also recommends the same. David Mendonsa has mentioned it on his site. Though I could not find it on ADA site.



It can be clarified as - The recommendations for testing BS after first bite is 60min. for peak and 120min. for how the BS returns to near normal levels. If someone decides to measure his peak value and if he measures his BS 60min. after his last byte (as you have mentioned) then he will miss the actual peak value. (60min + whatever time taken for meal)


Thank you. Very useful information. Prior to starting the lwmdr, i checked my PPBS in the hospital, 90mins after breakfast of idlis and it was 195 and I thought, it is too high and need to do something. 1 month prior to that, my ppbs was about 125 and that was 2 hrs after breakfast and I thought difference should not be so much for that 30 mins difference. Now I understand it is not abnormal. Those days, I used to take neem, karela, etc., and reduced medicine, and was regularly doing excercise. After seeing 195 after 1.5hrs, I thought none of them are working and I stopped that leaf treatment.


You are welcome yvjanard.


ShooterGeorge, this is the second time I am seeing this. What a piece! also, good input from other contributors.


Thank you norreal.


Excellent argument, Shooter. Makes complete sense to me.

Thank you for bringing in some clarity.


Thank you friend.


Test at 1.5 hrs after meal will give a higher value for PPBS. This can be confirmed by testing BS at 1.5, 2.0 & 2.5 hrs continuously. Some of my posts also will show this.

Testing time selection depends on the requirements.


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