CGMS profile

[MarkMunday]

Last week, I got hooked up to a CGMS (contiuous glucose monitoring device) for three days. The main purpose was to get a handle on what was happening to my blood sugars overnight. The graph is displayed below.

I was having difficulty keeping my blood sugars down during the monitored period. I realised afterwards that the Novorapid cartridge I was using had gone bad. Unfortunately, a number of unscheduled correction boluses make the graphs hard to interpret.

The graphs clearly show the dawn phenomenon effect. Blood sugars increase steadily from 12:00am to 6:30, when I have a correction bolus. Early morning lows on the 23rd and 24th were the result of correction boluses from the previous evenings.

It has been an interesting exercise. But, because of the Novorapid control problem, I still don't know if I have got the Lantus basal rate right. :confused:

Cheers,

[Funnygrl]

Wow, this is really interesting. It's cool how all your days follow pretty much the same pattern. That will be helpful. I have always wanted to go on a CGMS, but never have. That's odd that you had trouble staying low enough, but you were always too low around 1 AM. Do you ever wake up to trat those lows?

[eevee]

If you could just fix that DP problem Mark, you maybe won't get that 8am - noon rise.....if only....!!
I used to think I had to go to bed with a bG around 10.0(180) but I now know I get better fasting numbers if I am around 8.0(145). Mind you I don't go to bed until 1a.m. and I have my Protophane shots 11am/11pm...usually I have a smallish slice of cheese, or a slice of ham.
You are concerned about the correct basal...have you done that fasting test (say 'til midday-1pm) where you only have your longer acting working..??

Cheers........Eve

[MarkMunday]

Those lows are a bit worrisome. The low of 2.2(40) in the early hours of the 24th (the blue line) was partially caused by a correction bolus at 10pm the previous night (the yellow line). But I didn't wake up. The blood sugar bottomed out 2:30 and started rising steadily as it usually does. Wonder if there could have been some rebound effect here.

The low at 12:30 am on 23 Oct (the yellow line) wasn't preceded by a correction bolus. The blood sugar also went down to 2.2 and I woke up this time. A couple of teaspoons of dextrose in water quickly bumped the level back over 5 (90) and I went back to sleep.

I didn't now I could sleep through such low blood sugars. This has been a useful lesson. I have woken up with a blood sugar of 1.1 (20) and still been able to help myself. So Hypo Unawareness is a bit of problem. In the future, I will be having a low GI snack before going to bed.

A fasting basal test sounds like a good idea. But I will probaly have to have a correction bolus first thing in the morning. Otherwise the blkood sugar will just keep rising.

Cheers,

Mark

[eevee]

That fasting test probably does work best if you are making some of your own insulin, or start out with a good fbg. I think the theory is to test how well the basal holds up when not eating.
You mention bolus corrections..at what number do you feel you need correcting, and by how much..how late in the evening...?? Are you taking as much lantus as you were on NPH/protophane. Have you tried changing the time you have the lantus..?? I know it is supposed to be peakless, but....
When I look at my diary I can see the difference between bedtime bG of 8.0 with no correction (fbg 5.6 - 8.0) and a corrected 10.0 at bedtime with resulting 10.00-12.00 fbg.
Most days the graph shows a big dip in afternoons...maybe a little less bolus at lunch...??
I think you are very brave putting your graph up, but I find it very interesting, and you don't have to answer my questions if you don't want...i won't be offended...lol..
Cheers......Eve

[debaroo]

Hey Mark i did the same test here in Canada and thats how we found my problem out over nite and having some lows and not feeling them at all....i loved wearing that glucose machine and punching in all the info and then looking at the graph...if anyone out there is having troubles over nite with there control this is the way to go...and the one i had on was from minimed...have to say very worth it to wear it for 3 days

[archimeech]

I actually have modified my basal rate at night to counteract the dawn phenomena. I took it upon myself to begin to increase my basal by 0.1/ 1/2 hour and gave myself a sign curve peaking at about 5am and then dropping off again at about 8am. It hasn't fixed all of my night time highs but has reduced the number of them and when it is high they are not as high as they used to be.

[Brent44a]

Mark, the trend lines shown for late night/early morning on the chart are remarkable. I believe I experience similar phenomena but am not sure of the details. I do know that I have not been able to crack the code on exactly what happens. I am looking forward to the day when the CGMS is more widely available which will certainly improve control options.

I have often wondered about overall BG exposure and what the effects are. For example, is it better to have a slight BG increase for an extended period of time (maybe a few hours) or to have a slightly higher BG increase for a shorter period? The averages may be similar with differing outcomes, and the ideal would be to have neither, but the approach one takes could depend on the answer.

[MarkMunday]

Brent, from the perspective of reducing the HBAic, a short-lived spike will have a a smaller effect than a sustained increase over a longer period of time. Ideally, the phisiological insulin requirement should be covered by sustained basal action.

Evee, I generally correct when my blood sugar goes over 10. If it goes over 12, I start feeling terrible. So I do whatever it takes to get it down again. And sometimes I over-correct ... I have also realised that the Novorapid cartridge I was using was not working properly, which caused a lot of confusion. It was the extra over-lapping correction boluses that caused the rollercoaster ride. It was unfortunate that this happened while I was busy with the CGMS.

Things have improved since I started the new Novorapid cartridge. But the night-time increase in my blood sugar levels, as reflected in the CGMS graph, goes on for too long nevertheless. The DP probably is partially responsible for the increase. But it also looks like I am running out of insulin in the early hours of the morning, from about 20 hours after my last morning Lantus shot. Splitting the dose reduces the severity of this. I split the Lantus dose evenly between 6:30am and 6:30pm shots.

I did a fasting test to see if there is a similar effect in the afternoon - 20 hours after the last evening shot. I skipped lunch and the corresponding Novorapid bolus. And, sure enough, my blood sugar increased from 6.2 to 9.8 between 1:15pm to 7pm.

Not a lot I can do, really. Lantus is supposed to last a full 24 hours. But with me, it clearly doesn't. A pump would sort this out. But they aren't funded here, and I just can't afford one. :(

Cheers,

Mark

[eevee]

Have you considered going back to having your full lantus dose at 6.30pm and having a smaller booster one at 6.30am to 'background' you through the day..mostly relying on the two Novorapid boluses.
What about a two-thirds 6.30pm and a one-third 6.30am.
I don't believe you are getting enough lantus overnight. Maybe what you estimate to be the correct amount is a bit low..??
I also think there is a 'flaw' in the notion that lantus, split evenly, can deliver the proper level. It certainly wasn't designed that way.

Cheers.....Eve

[gettingby]

Mark,
I hope that you get things straightened out soon. Getting the correct doseages can be a little tricky. Hopefully things will get better soon. Sorry about the pump. You sound like the perfect candidate for one.

[MarkMunday]

Evee, you are quite right about Lantus not having been designed to be used in split doses. The whole idea is that Lantus is supposed to be peakless and work over a full 24 hours. But 6 of the 22 respondents in this poll (http://www.diabetesforums.com/showthread.php?s=&threadid=2645&highlight=Lantus+Poll) split their doses. And my endo has also found that Lantus doesn't last the distance for 25% of his patients.

Splitting the dose is by no means ideal. But it does provide 1/2 strength basal action during the gaps before the respective shots. You are right about me not getting enough insulin overnight. Taking all the Lantus at 6:30pm would overcome this. But I would have to deal with a much bigger peak at 9:30 - 10:30. This is getting close to bedtime and I really want the basal action to have settled down for the night by then. I tried taking the full Lantus does at bedtime (about 10:30). But found that I kept waking with a hypo at 1-2am.

Thanks for the comments and suggestions. They have got me thinking. I really need to revisit and review some of the tests I have done over the last three months. I may have mis-interpreted something ...


Cheers,

Mark

[archimeech]

Mark is getting the pump the issue or is it the cost of the supplies?

[MarkMunday]

By way of feedback, I tried having a snack before going to bed. And, to my amazement, it worked! I have been sleeping through the night. And I have stopped waking up with high blood sugars, as the CGMS graphs above reflect. The DP is obviously not the problem I thought it must be. Nor am I running out of insulin in the early hours of the morning.

This has surprised me because, the last time I tried it while on Lantus, having a snack before bed caused me to go high. And wake up with a full bladder at about 2am. I also thought that, with Lantus, a snack shouldn't be required.

This also raises the question of how low the BS needs to go before the liver kicks in and causes a rebound. One of the graphs show the BSL climbing consistently from 5.3, which really isn't low. I guess this highlights the danger of making assumptions when when diagnosing control problems.

Anyway, I am happy report that my control has improved enormously. Thank you all for your suggestions and comments.

In answer to your question, archimeech, both. Neither the capital cost nor the supplies are funded here by medical insurance or the public health system. Not yet, anyway.


Cheers,

Mark

[archimeech]

Glad to hear you're doing better, but so sorry that your health system won't help with the pump. I guess socialized medicine has many pitfalls, just like ours.

[Funnygrl]

Mark, may I ask, did it hurt when they put the set in? I am kind of interested in getting this done, but I doubt it will ever happen.

[MarkMunday]

Funnygrl,

It didn't hurt at all when the probe was inserted. And after half an hour, I wasn't even aware of it. I clipped the unit to my skants at night and it wasn't a problem. My first shower with it attached was a bit awkward. But the next one was a lot easier.

I can see now how one could get used to wearing a pump. I was having some difficulties with my control at the time, which was unfortunate. But using the CGMS was nevertheless a very worthwhile exercise. It gave some insights that would otherwise have continued to evade me.

Cheers,

Mark