Insulin to carb ratio

For several years I’ve worked with a 1:3 ratio of insulin to Grams of carbs which has worked very well for me. A new doc wants me to change to 1:6 or 1:8 because I started having lows about two a.m. after three days of this my average bg went up to 9.1 from 6.1 with no apparent effect on the nighttime lows. Now I find out that compression may be causing these lows, well she did tell me to to a blood stick to see if they were real, but I don’t have an alarm system and don’t really want to switch. She’s also changed my Toujeo, used happily for last five years to Tresiba. Don’t really have any results on the Tresiba yet but can anyone advise?

This change would possibly improve your overnight lows, if indeed BG checks confirm them. But it can take several days for Tresiba to even out since it may stay in your system longer than Toujeo.

Its possible just your night/dinner time carb ratio needs changing, if the meal bolus was contributing to your overnight lows. 1:3 changing to 6 or 8 is too big of change, but I would suggest fasting/no dinner meal and first get your nighttime basal to prevent lows.

Compression lows are usually associated with pump usage, but seems possible large basal dose could do same just before bedtime. I think Tresiba can be taken anytime, and many prefer it. If a large dose, it could be split to half dose twice a day.

Not fun, but setting alarm and doing night time testing is best way to know what works.

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Whats your tech?

Tresiba is supposed to be better at preventing night time lows, but I agree that you really need to find out if it’s your basal or close to bedtime/dinner bolus dose causing the low, or if you are even having a low.

So the first thing I would do is what @MM1 has said and set your alarm to do a finger stick test a couple of nights to find out if you are actually dropping. If you are dropping the next thing would be to fast at least 6 hours before bedtime so you aren’t dealing with a bolus dose to find out if you have too high of a basal dose.

If you need 1 unit to 3 carbs all day, then you need it. But for a lot of us our dose needs change during the day. And it can really vary person to person. For instance I rarely eat in the morning as I have DP or FOTF sometimes and find I need bigger doses before 11 am and it’s hard to control, so for me I usually skip eating before 11 am. But if I do it is at 1 unit per 3 carbs. But by afternoon/night I become more insulin sensitive and usually take 1 unit per 7 carbs. Some people are completely the opposite.

Usually when you deal with a compression misreading from a CGM type device you will get a sudden low that changes pretty significantly after the pressure is off of it. So for example my alarm goes off because it says I am low, really low but I do a finger stick and I am actually completely normal, I look at the reading again and because the pressure is off of it I would now see a “normal” reading. The compression causes fairly fast changes in it’s reading.

I would suppose you could have a slow decrease from it slowly not working right, I’m not sure. But this is where a finger stick at night would be helpful to compare against the low at night. I am thinking you have a Libre? Libre’s notoriously read lower than you are and some can be off by quite a bit. Some people have complained they have ended up with higher A1C’s than they expected because they counted on it’s “lower” numbers for dosing and control.



Hi @VirginiafromUK - The only definitive way to confirm your 2AM lows is to finger stick-check with a meter. Apparently you have a CGM, and you’re on the money with respect to compression lows, which unfortunately plague most of us wearing these devices.

@MM1 & @Marie20 also made an excellent point about insulin:carb ratios varying throughout the day. Years ago I had thought my I:C ratio was 1:15 - all day long - and I used that ratio to dose for carbs and elevated BG’s throughout the day. What a mistake.

Many diabetics have to deal with DP or FOTF each morning (dawn phenomenon or Feet on The Floor syndrome). Both of these are the result of adrenals, including cortisol, glucagon, epinephrine and human growth hormone, being released by the body causing the liver to release glucose and increasing your insulin resistance. Which is to say temporarily raising your Insulin:Carb ratio.

Any number of other metabolic processes can also have the same effect on your insulin:carb ratio (metabolic syndrome, stress, menstruation).

As long as you’re aware of your body’s changing insulin needs, you can alter your I:C ratio and deal with lows / highs accordingly :grinning:


I agree with @MM1, @Marie20, and @Jimi63. I am more insulin resistant in the morning and more insulin sensitive the second half of the day. My current insulin to carb ratios are 1:4 from midnight to 1:00 pm and 1:8 from 1:00 pm to midnight.

These numbers, however, can and do change. Sometimes they work for many months but then my body decides it wants more or less insulin. It’s our job to detect that change and respond. It’s not an easy job but it is possible to do it well enough.

I agree that fasting for 4-6 hours before bedtime will help you to troubleshoot this scenario. Set your alarm, fingerstick, and analyze the next morning. You may need to do this for a few nights in a row.

Maybe your doctor’s suggestion of going from 1:3 to 1:6 or even 1:8 is too aggressive. Doctors do err on the side of caution. If you do the evening fasting and alarm testing you will quickly discover the truth for you. At least for now, things can and will change! Good luck with this.


It doesn’t make sense to me to change overnight lows in this way. But, I don’t have much info. Maybe there is a reason. IDK.