Bedtime vs Daytime

During the night & shortly before bed I often have CGM & BG numbers that do not match. Here are the 2 most common scenarios:

  1. ~1 hour after my shower, but before eating my bedtime snack: BG significantly higher than CGM, but usually return to similar before morning
  2. Under covers at night: Being under the covers in bed, regardless of sleeping position, cause slightly lower CGM numbers (not necessarily alert or out of range low, but still lower than it really is). After getting up for 10 or 15 minutes, it will usually come back to correct, but then back down if I get back in bed. If I lay in bed without the covers, this problem does not usually occur

Has anybody else had either of these problems? I use the Guardian 3 (with the recently updated transmitter).


People may have widely divergent ideas about what sort of difference is considered large or small in terms of readings between a meter and a cgm system.

What sort of differences (in terms of numbers) are you seeing?

You mentioned using the Medtronic Guardian 3 (with updated transmitter).
Which meter do you use?

I have not heard of or experienced the rise with the morning shower. The overnight slightly lower than meter reading is something I do experience.

Note: I am a Medtronic ambassador. My opinions are my own. They did not pay me to say nice things about Medtronic devices or the company. OK, they sent me a shirt and a cup but even I am more expensive than that.

I probably should have been clearer about the shower scenario, that is before bed (not in the morning). My usual evening schedule is (on average):

10:15 or so: shower
1/2 hour or so after shower: BG Test followed by snack
After snack: Go to bed

As you can see, there is 1/2 hour (at least) after shower to allow my CGM & pump to reconnect.

I use the Contour Next Link 2.4

When you say this, are you talking about only if under the covers, or regardless of the position and whether you are under the covers? For me, it is normally only if I am under the covers.

My G5 reads too high and then sometimes too low after getting wet from either a shower or sweat. It usually reads ok again after 4 hours or so.

I am always under the covers. So under.

I take 10-15 minute hot shower every morning and my G5 Dexcom shows a post-shower BG rise of about 20 mg/dl and then takes about 15 minutes after shower for that BG to go back to where it was.