I'll show you mine, if you show me yours!

lark 27 · #1 (**permalink**) 10-29-2009, 11:52 AM

OK, that's just a provocative thread title, but the real question is what's your standard deviation over the last couple weeks?

If you're not familiar with looking at Standard Deviation, it is a very important number for us to look at. A person with a 120 BG average could actually be spending a lot of time at 200 and a lot of time at 40 and still come up with a good average BG and good A1C. However, by also looking closely at standard deviation it helps one get a better picture of overall D control. I've seen it recommended that a goal for Standard Deviation should be 1/3 or less of yourBG average. So if my average is 120, my SD should be 40 or less. Of course, we should also aim for our BG average to be good because it's not good to have a 200 average so that you're allowed a 67 standard dev. and still be at 1/3!

With that said, I feel like this standard deviation number is so very personal and somewhat strips me bare of any excuses(I can't hide from the reality of the numbers which I think I need to improve.) So, I'll show you mine if you'll show me yours.

However, first a couple statements. I have never tracked standard deviation prior to having a pump. I now use the minimed paradigm with the CGMS so I can upload the data and it gives me standard deviation for sensor data as well as meter data. If you don't have a meter or pump that can do standard deviaiton you can enter values manually at: Standard Deviation Calculator Beyond that, I'm not a mathmetician so I can't help you out.

I think the data for both sensor and meter is slightly flawed, so that's what brings me to wondering if some of you would share your data so I can get a good bench mark. The meter data is flawed because I become a hyper-tester when I'm either low or high so although I usually don't get above 200, when I do, I'll test a couple times to double check. Then I'll test often to make sure it's coming down. For lows, I'll also test often to make sure it's coming up. So I end up with a larger percentage of high/low tests than is actually true.

The sensor data I think is flawed because it tends to not quite show the true glucose levels for either highs or lows. Perhaps I should average the two.

Anyway here's my data.

Previous two weeks BG average:
Meter: 119
Sensor: 115

Previous two weeks Standard deviation:
Meter: 51
Sensor 31

Thanks for reading and replying,

lecsiy · #2 (**permalink**) 10-29-2009, 11:59 AM

Average of 6.7 - 120
With a SD of 2.6 - 46
Highest 14.7 - 264
Lowest 2.6 - 46.8

Based on 30 days of data. Very recently diagnosed.

Now. Whats yours!

Lecsiy

foxl · #3 (**permalink**) 10-29-2009, 12:03 PM

Sorry -- my $30.00 meter software DOES NOT CALCULATE SD!

cwathne · #4 (**permalink**) 10-29-2009, 02:06 PM

Quote:

Originally Posted by foxl

Sorry -- my $30.00 meter software DOES NOT CALCULATE SD!

what?, you're too lazy to calculate the mean, then subract every blood sugar test value from the mean, then square each of those values, then sum all of those squared values, then devide by one less than the number of blood sugar tests?? Yeah, me neither

lark 27 · #5 (**permalink**) 10-29-2009, 02:57 PM

Quote:

Originally Posted by cwathne

what?, you're too lazy to calculate the mean, then subract every blood sugar test value from the mean, then square each of those values, then sum all of those squared values, then devide by one less than the number of blood sugar tests?? Yeah, me neither

Thanks for explaining the formula, that is quite complex. I would think it wouldn't be too hard for the meter manufacturers to include that equation into the meter so that we could just get that result much more easily.

Oh well, I trust there's some folks out there besides myself and lecsiy that can access that data relatively easy. Also, there is the link to the standard dev. calculator I put in my first post, so that allows you to simplify it to the tedious task of just entering the values from the last week or so, and it spits out the SD.

It Ain't Over · #6 (**permalink**) 10-29-2009, 03:17 PM

Or I could just get my Caselink to work. I take it there is no driver available for Vista 64.

inkvisitor · #7 (**permalink**) 10-29-2009, 03:35 PM

Thanks for bringing this up - it is an important part of blood sugar monitoring and control.

I use sugarstats.com to log my readings so I exported the last month in to excel and used the STDEVP function to calculate it...66! Eeek! I can definitely tell my control has been altered (for the worse) because of stress and being busier than normal - I need to take a easy..

shiftzor · #8 (**permalink**) 10-30-2009, 06:16 PM

Mines in my sig. Its amazing just how much SD is overlooked and i guess its mainly due to lazyiness

. SD is very important as an A1c is simply not good enough.

JJM335 · #9 (**permalink**) 11-02-2009, 08:41 AM

Quote:

Originally Posted by shiftzor

Mines in my sig. .

Hi Shiftzor:

Looking at your sig, I suspect you may be using an outdated conversion formula to go from A1c to average Bg.

The most up-to-date conversion formula, ADAG (A1c-derived average glucose), was derived from a large scale study using CGMS. The earlier studies were based on smaller samples in which subjects were spot-monitored on a limited number of selected days over a 3 month period, using meters. Despite the questions about the accuracy of CGMS, the ADAG data are obviously more reliable since they represent the results of continuous monitoring throughout the period of the trial.

You can access the on-line converter at:

A1c/Average Blood Glucose Conversion Using the ADAG Formula

Joel

lark 27 · #10 (**permalink**) 11-13-2009, 11:47 AM

Thanks everyone for your replies. I was away from the forum for a bit so just now am getting in to look at these responses. I met with my doctor yesterday who had no real knowledge of the significance of SD. I've moved anyway so need to find a new doc, and I think (SD) that will be one of my "interview" questions to test the doc's diabetic literacy.