Working out the dose...

Stuboy · #1 (**permalink**) 02-07-2008, 05:32 AM

Ok, so im rubbish at maths...

I've been trying 10:1 ratio on my novorapid but im going low waayy too much with it... it might still be leftover higher lantus dose as well still, but i think my ratio is more like 10:0.75...

what's the formula for working out the dose for a ratio? I used to have it written down somewhere but i can't find it

if 10g carbs is 1 unit, and you have 50g carbs, you just take 10% of the carbs... but i just can't work out for 0.75.

hang on i think i've just clicked...

Total Carbs / 100 * 7.5?

is that right?

i had 5 hypo's yesterday and already 2 today

xMenace · #2 (**permalink**) 02-07-2008, 06:03 AM

I prefer to think in terms of units of insulin, and I describe it as I:C or 1:10.

.075:10 equals 1:13.333 (10/.75=13.333), so for every 13.333grams you need one unit of insulin.

SueM · #3 (**permalink**) 02-07-2008, 06:09 AM

Hi Stu, is this what you are looking for?

Carb Factor From The 500 Rule

Stuboy · #4 (**permalink**) 02-08-2008, 01:38 PM

Thanks to both of you.

Sue, that's the formula that the diabetes consultant (insulin expert) gave to me that i'd lost.

One thing i dont really get about it though, if 500/TDD is the carb to insulin ratio... how can you work that out if you dont know what the carb to insulin ratio is in the first place to accurately find your TDD?? lol or am I just being dumb!?

looking at what i've had over the past three days...

on a 3 day average i have 18u a day fast acting. i have 24u lantus. so that's 42u insulin...

500 / 42 is 11.9 (12 for the sake of argument).

so that means my carb to insulin ratio is 12:1?

which if im seeing that right, means my guess of 10:0.75 is quite close? I prefer seeing it as 12:1 to be honest lol.

JediSkipdogg · #5 (**permalink**) 02-08-2008, 02:00 PM

I hate the 500 rule as it's a very generic rule. It's about as generic as the rule of thumb that a person should have 1 unit of insulin for every kg in weight. It doesn't take into account insulin resistance or sensitivity.

If 1:10 is taking you too low then try 1:11 and keep trying 1 unit at a time. And trust me, working in 1 unit of insulin is much easier than .75 units of insulin. But do it the way you like.

Stuboy · #6 (**permalink**) 02-08-2008, 02:17 PM

I totally agree... i'd just forgotten the rule.

The only thing is... what to do when you're stuck between units... i just had a small cheese cake... 30g carbs (nutritional info from the pack).

if the 500 rule is right and my ratio is 12:1 then i need 2.5 units... so i took 2.

I could also go back to the novopen junior... even if it does look like sometime from a smarties party lol.

I think you're right though, i might try 11:1 before i jump to 12:1. Thanks Kev.

Alice · #7 (**permalink**) 02-08-2008, 02:17 PM

Here's a really weird way (that my mind seems to work, I guess)...I'm 1:15....

So I just know my multiples of 15 up to a pretty normal range.

15-30-45-60-75-90 carbs equals 1-2-3-4-5-6 units of insulin.

I rarely eat more than 60-75 g carb even in a big meal. Typically I'm taking 2-4 units or 30-60 carbs.

To this base, I might add for mystery ingredients, PMS, etc. Or, I might then split the dose for two injections apart for slow carbs such as pasta, pizza, rice, etc.

JediSkipdogg · #8 (**permalink**) 02-08-2008, 02:23 PM

Quote:

Originally Posted by Stuboy

The only thing is... what to do when you're stuck between units... i just had a small cheese cake... 30g carbs (nutritional info from the pack).

if the 500 rule is right and my ratio is 12:1 then i need 2.5 units... so i took 2.

You can either try a pen that does half unit doses (which I'd recommend) or do the rounding rule. You just have to round to whichever you feel more comfortable with, running higher or running lower.

Alice · #9 (**permalink**) 02-08-2008, 02:26 PM

I usually "round up" on meals and "round down" on single 15 carb item/snacks. This has prevented many hidden carbs in meals from throwing me off...and small snacks from taking me too low.

Stuboy · #10 (**permalink**) 02-08-2008, 02:47 PM

good advice, thanks!

xMenace · #11 (**permalink**) 02-08-2008, 03:43 PM

Quote:

Originally Posted by JediSkipdogg

I hate the 500 rule as it's a very generic rule. It's about as generic as the rule of thumb that a person should have 1 unit of insulin for every kg in weight. It doesn't take into account insulin resistance or sensitivity.

If 1:10 is taking you too low then try 1:11 and keep trying 1 unit at a time. And trust me, working in 1 unit of insulin is much easier than .75 units of insulin. But do it the way you like.

The only use I see for the 500 rule is for brand noob type 1's to get them started while in the hospital under close supervision. Throw the literature away and start with small steps from where you are now. The only "should" in this game is whatever gets your sugars controlled.

Stuboy · #12 (**permalink**) 02-09-2008, 04:09 AM

im not a complete noob... been D for over 18 months now, but i did loose my way, so it's a good starting point. i was using 10:1 the last three days, and i was hitting a few lows... which i expected because i lowered by lantus so still had some of that in my system with high doses of rapid, but three days on im still getting a bit too low for comfort, so working out on the 500 rule it comes back as 12:1, so im gonna try 11:1 over the next few days to see how that goes.

I've dug out my novopen junior for half units and for now i'll round down to the nearest half.