Question about validity of basal testing

im looking into basal testing. i am very active person, cycling to and from work every day (about 50 minutes total) or walking the same distance (about 45 minutes each way).
i also do from 30 minutes to 1 hour of exercise almost day-kettle bells, zumba, astanga yoga, power walking. i never take buses or anything, walk and cycle everywhere, use every opportunity to exercise, as i am aware that i can become insulin resistant and insulin can make me fat and that exercise will help with glucose levels.

i take 1 unit of novorapid for breakfast of 30 carbs, 2 units of levemir in the morning and 7 at night. i dont take any insulin for lunch on workdays because i eat low carb and cycle to work straight after. dinner is very late-about 11pm, due to working hours and i eat low carb and usually dont inject.

at weekends, if i am going to be sedentary after lunch i do a unit of novo because i need it. if im going to indulge in cheesecake or something i always inject for the carbs.

everywhere i read about basal testing says i shouldnt do any exercise or eating while doing basal testing. the eating part i can understand because i wouldnt want the bolus for food interfering with the test. but what about the exercise? if i dont do my regular exercise, wont the basal test give me results that wont be right for my normally active days? the results of basal tests where i dont do any exercise would surely give me false results because that sedentary doing nothing does not reflect my day to day. i want my basal to keep me even all day when im exercising. so shouldnt i do basal testing with exercise? what is the premise behind this no exercise thing?


I don't do any basal testing so I am not perhaps the best person to answer this. I believe the premise of not exercising is that exercise will likely "cook" your numbers so the basal may be set a bit low if you include say a 20 mile bike ride in your basal test. To test your basal you only want a basal vs. body matchup, not anything else, or the test is not quite accurate.

I "fudge" (ha ha...) this by using my fasting #s (before meal...) to evaluate the accuracy of my basal numbers and my post-meal numbers to evaluate bolus ratios. It's not always accurate but I usually run close enough that the adjustments are more like fine tuning (+/-.025U/ hour, sometimes .050 if things appear really whacky...).

I am a total creature of habit and eating is one of my many habits and I don't find that I need to stop eating once/ year or every 6 months to test my basal "more accurately." I have noticed at times that when I am cranking the basal up, it may result in cutting ratios back as, during mealtimes, there's some "overlap" where both basal and bolus insulin is cranking away. For a long time, I had cranked basals around every meal and then realized "wait, you can just put 'that' insulin in with a ratio and probably do better and, most critically, be more accurate on weekends when mealtimes varied more." That probably seems obvious but I find it interesting to sort of oscillate around the various numbers. Lately, I'm using a lot more temp basals after meals but boosting to cover highs (and by highs, I'm talking like 120...OCDiabetes to be sure...) and lows (60s, same thing) as if it drifts where I don't want it, it seems as if a small basal adjustment can do the same thing as a small snack or walk around the block and is a bit more mellow than a correction bolus for a "nudge", not as much IOB on the high/ low corrections.

My understanding is that basal insulin delivery is intended to metabolize the glucose released by the liver. If your exercise habit is consistent in intensity and duration then I would not drop it when basal testing. This is your physiological "normal" day.

That being said, if you did take one day off from exercise to test your basal rates, I'd be curious to know if the results were much different. Perhaps your liver's output of glucose will not change much on an occasional day off from exercise. Your personal N=1 experiment will settle this question.

Congrats on sticking with your exercise routine. It will help maintain your sensitivity to insulin.

I also don't bother with basal testing. If I consistently see that I'm high (or low) at certain times of day, I tweak the basal for the period two hours before the offending numbers. When I was on MDI I just looked to fasting, bedtime and the in-between numbers out of range of meals and if those were consistently high or low I altered my basal by a unit or switched its timing. It's not an exact science but then neither is long-acting insulin! Personally I think basal is more meaningful for those on a pump as it can give you exact hourly data as to when doses need tweaking. Even on a pump though I just "look to the numbers" for info on when tweaking is needed.

thanks for your responses. such a turn off, this basal testing with its no eating malarchy....maybe ill just leave it where it is.

I wouldn't say to leave it where it is if you are running into the same issue on any sort of regular basis, like a low every day after lunch or after breakfast or before dinner or during your bike ride. If an "experiment" is repeatable and has an unpleasant result, it's often very cathartic to try an adjustment, find out it works and remove the unpleasant result. When I do stuff like that, a lot of times, it will remove the chore (testing, treating, etc.) from my daily activities so I can do more fun stuff.

For you, I wouldn't worry about being "insulin resistant" until you are taking 80-100U of insulin and getting diminishing returns on your shooting of it. Same thing about fat. I think you'd like it more if you figure out your basal rate by the stuff that I think we talked about in that other thread, aim for a balanced approach, but if you run low, try a small adjustment, 1/2 unit or whole unit or whatever, over the course of a day (1/48U/hour or 1/24U/hour...) and see what happens for a few days? Bring extra snacks (which seems counter-intuitive but a lot of times when I cut basal back, I will seem to encounter some lows...sometimes because I'm not doing little hits of carbs here and there to boost out the lows like I do when I'm running a shade too much juice...) and test strips or whatever and see how it goes. If, after a few days it's dramatically horrible, you can always go back but, if you see a change that in some way improves things in some manner (not just higher or lower but smoother, more fun, etc...), then you've done a great thing and can celebrate!!

AR - You’re right about BGs dropping after reducing basal rates. It doesn’t always happen to me, but I’ve witnessed it more than once to know it’s true and counter-intuitive. For overall successful BG control, the science and math of diabetes management must be integrated with the art of diabetes management.

I like to use the science to get me in the right neighborhood and the art to make subsequent adjustments. If I rely only on “gut instinct” and SWAG, my BG performance suffers.

I meant "I think basal testing is more meaningful to those on a pump.."

Do you have highs or lows routinely at rising or in between meals? If not, I wouldn't worry about it! If yes, then I would suggest increasing or decreasing by a unit and seeing how that goes for a few days. To do basal testing just to do it seems like a waste of time and energy to me.

you are so right acidrock, just getting frustrated here with the D. yeah zoe, some lows seemingly coming out of nowhere usually due to exercise, so not really out of nowhere. but with little bolus in me! 3 hours after bolus and my carb count is good because 2 hours post im at 140 or a bit under, just where i want to be. i think of basal as innocuous for some reason.

the more typical situation is the end of my workday at 10pm. theres usually not any bolus (only bolus in the mornign on workdays)in me at the time and im gobsmacked that 2 units of levemir in the morning can do that on my cycle home from work. ill measure at about 7pm at work and ill be at like 95 or 100. since i know ill be dropping (and i have no idea why, my personal physiology?) i have between 5 to ten grams of carbs with some fat. i know that 3 hours later when its time to go home, ill be at 80 and will have to eat more. if i didnt test and have a glucose tab for the way home, id be low on my bike every night. im aware of the possibility so i test and treat but i would just like to not have that and go home and test and have dinner. just seems crazy for the two measly units i take in the morning. or could this be from the 7 units im injecting at 830pm???
maybe looking for the whys is just as much of a waste of time as basal testing-i agree with you zoe, basal testing to me seems like a waste of time.

maybe ill decrease a unit in the daytime and see how i do on one unit during the day. art and science, just like teaching, terry...i should have this down by now!


If you're splitting your shots, it seems to me that it would be more likely that the larger shot in the evening would be the one "gobsmacking" you. 7U would calculate out to .292U/hr if it lasts 24 (7/24) or .39U/hour if it lasts 18. I haven't ever tried levemir but it seems to me like conceiving it this way may have some use. An 8:30 shot would still be "firing" at that time plus you'd have the morning "whiff" of .041U/hr added in, plus the AM 'Log shot chasing breakfast. Another phenomenon might be "peaks" which would be if the levemir isn't totally flat but maybe runs up to .3-4U for a few hours as the insulin peaks.

This effect is more pronounced with NPH, where the peaks have only a 53% chance of occurring when they are supposed to (which makes balancing BG very challenging...) but I think that people report it with lantus/levemir. There may also be some fluid dynamics involved with a larger shot deploying a bit differently, as there's a study Dr. Bernstein cites, about shots> 7U having absorption problems. Granted, your shot is "only" 7U but maybe it doesn't deploy itself quite the same way and causes a "bump"? If there is a bump, it may be productive to try to shoot the evening shot later to delay it until after your AM bike riding. This would have the other advantage of perhaps hitting around lunchtime in which case the bump could actually have some utility. Maybe not enough to sustain an order of cheese fries by itself but well, you know...

I sort of wish I could report on experiences with levemir more usefully but having a "pump-like" conceptualization of how it plays out might be useful for some adjustments. It would be very challenging to observe this but, as we all know, diabetes is challenging...

I do basal test, especially in rough times. It helps me see the true effectiveness of my basals without food and exercise as variables which helps me make better choices.

I would say this, however. If you are exercising that much and it is not sporadic, I would keep up the exercise while basal testing. If it is a constant, it has an impact on your insulin needs and should be considered.

no but those lows are happening at 11pm, not am, and im thinking those 2 Little units at 930 in the morning cant be doing that! you think the shot the night before would affect a full 24 hours later, or that it could be the 7 units of levemir that is injected just hours before at 830 pm. guess teres only the trial and error method to find out. :( i hate the trial and error method, wish my doctor could just say, "well its obviously X, so do Y". that would just be so awesome.

that means id have to exercise in the morning without coffee, doesnt it? :)
maybe ill just do a long walk in the park then...

Your body's natural production of insulin could definitely be a factor here. You haven't been diagnosed that long ago and your insulin needs (external injected) are very low. That may very well mean that your pancreas still cranks out some insulin.

Maybe it works better during some parts of the day than others. You've committed to a certain basal profile based on the quantity and timing of your two levemir shots. When your pancreas decides that it will put out a normal basal rate, then the added levemir will result in a hypo.

As much as an inconvenience that basal testing is, it may reveal a daily pattern of endogenous (internal honeymooning pancreas) insulin production that you could use to plan your two levemir doses.

Just a thought.

OK. I am going to get into trouble for this, but....

Does coffee regularly raise your blood glucose readings? When I go for fasting work, water, black coffee and tea are OK. If no consistent problems, drink the caffeine.

I have, over the years, had very inconsistent highs from coffee. When I retired, I switched to iced tea which has had no adverse effects high BG readings from it in the last year.

That's a great idea about the temp basal's AR. I might give that a try too, as I'm to lazy to be bothered with basal testing. LOL I'll admit it. But sometimes I think just that .25 +/- makes a big difference and smoother too than a correction bolus or glucose or food for semi low's.

I'm not a coffee drinker so much, but I do chug away at some Diet Pepsi, I haven't found caffeine for me to effect my BG readings at all.

Terry, maybe youre right, it must be this internal insulin production that is working better in the early evening. why doesnt a páncreas just spit it out evenly? pain in the arse, this is.
so im gonna have to do this testing thing. thanks for bringing up the endogenous insulin, hadnt really considered it. you know just when i get it figured out, its gonna change, right?!? haha!!

yeah, does nothing to mine either. thank god, what would i do without coffee?!?