Welcome to Round 2 of my new blast-from-the-past series here at DiabetesMine. Once again, I note how little things have changed in four years! This post originally appeared exactly four years ago to the day, but if I didn’t tell you that, you might not notice. That’s because using the standard deviation for evaluating glucose results remains a much-discussed but not universally accepted method. Enjoy…
Standard Deviation Buzz
There seems to be a lot of buzz about the fact that it’s not just about A1C’s anymore; rather, it’s about using the Standard Deviation to evaluate the success of your diabetes management. If you think about it, it’s common sense really: a simple average of your blood glucose over the past three months doesn’t tell you how far you’ve strayed from the ideal range. You may get an excellent “average” number that is nothing but a middle point between the highs and lows you’ve been experiencing.
At an informational meeting a few days ago, I learned where all the buzz started. The idea of concentrating on Standard Deviation is not entirely new, but has found an avid proponent in Dr. Irl Hirsch, a Type 1 diabetic himself, who is medical director of the University of Washington Diabetes Care Center.
He apparently presented his initial paper on the Power of the SD at the Clinical Diabetes Technology Meeting last April, and his definitive article on the subject is slated to appear in next month’s Diabetes Technology and Therapeutics Journal. This publication is interesting in itself, as it is driven by the Diabetes Technology Society, a group which I’ve discovered is headquartered here in the California Bay Area very near me! This group organizes two annual conferences, the clinically focused April meeting mentioned, and also the Annual Diabetes Technology Meeting in November. Both are intimate events for the movers and shakers in D-technology.
SD formula for diabetes: A1c x SD/100. Find that confusing? Try the online Standard Deviation Calculator here. Also, if you can manage to export your downloaded BG montior data into Excel, that program will calculate the SD for you.
The theory is that the greater the deviation in your blood sugars, the more likely you are to experience mircovasular damage in eyes, kidneys, etc. Dr. Hirsch suggests that diabetics should aim for an SD of one-third of their mean blood sugar. So, if your mean blood sugar were 120 mg/dl, you would want your standard deviation to be no more than 40 mg/dl, or one-third of the mean.
Anyone out there using the SD formula successfully yet? Has it helped you improve your control just knowing how much you are “all over the map”? Do share!
I’m ashamed to admit that I don’t download my glucose meter results — maybe I’m too lazy, but heck, the rest of my life is already tracked by a half-dozen other spreadsheets (kids’ appointments, nanny schedule, work deadlines, dinner menus, and so on). So just haven’t had the impetus to fuss with D-Math. (You might say I prefer telling D-stories 
)
Thoughts? View the comment stream from 2005 here.
btw, this year I’ve actually been invited to participate in the fall Diabetes Technology Society Conference, in a panel talking about the most-needed types of “technologies to improve adherence and control of diabetes.” Any ideas on that angle are also very welcome.
Whoa way back.
The more things change the more they seem, uh, insanely the same.
Hmmmm.
As far as the in the Fall — health insurance for all PWDs. America can learn a lot from those across the pond. Not actually technology related but if one cannot afford insurance based on the way things are currently set here in America, how the heck they gonna afford any New technology???
Go to the root of the problem and things will get fixed. I am a realist, it Will take time. I know this. But come on. Enough with the darn technology already! Most can’t afford the basics Now!
I’ve used Dr. Hirsch’s stnd. deviation “formula” since you first posted it. I calculate it on a monthly basis – statistically, you need a fair number of measurements (BG results) to have any statistic, including your BG average and SD, mean anything – I’d say at least 30 or so measurements. And yes it does help me evaluate how I’ve done on the BG control front. Calculating your BG SD isn’t really a new technology, it’s just another way of seeing you much your individual BG test results vary from your average over some period of time. Not surprisingly, I’ve found it quite challenging to get my BG SD ratio below 33%. Also, it’s hard to relate your BG results to their effect on the SD. So for me it’s a useful but second-order measure of my control.
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My average glucose is 95, and my SD is 14.
Thats a ratio of 18%
-Lloyd
Our President has promised to defeat diabetes, poverty, and global warming and I believe he will. He said this in Denver and I was there. I hope he sees this CGM as a beginning to his defeat of diabetes.
Very interesting post!
Diabetics should aim for an SD of one-third of their mean blood sugar. The standard deviation is actually more important, because it has more to do with what people think of when they talk about control.
Llloyd says his avg BG is 95 and his SD is 14.
With all due respect, not even a non-diabetic is likely to be able to produce those numbers. That means that his readings are typically between 81 and 109.
If one can actually acieve an avg BG of say 120, it will still be a good effort to have one’s readings range between 60-180, which would mean the SD would be HALF the avg BG. That is at least do-able.
Thanks for giving us ANOTHER thing to get paranoid about.
Hi there,
I’ve been tracking my Standard Deviation for a couple of years now.
I’ve had type 1 for 33 years.
My results are better than the majority of the world who don’t obsess about results (and read blogs on diabetes), but there are some who manage better than me. Here’s what I do:
I currently use a spreadsheet produced by Kevin on the Parenthetic (diabetic) blog. (If anybody’s interested, google it and ask him for a copy.)
With the spreadsheet, together with approximately 20 tests per day (thankfully strips get a very large subsidy in Australia), and following the DAFNE principles for control (a program for measuring food and doses taught in the UK, Germany and Australia), … I manage an average glucose reading of 6.0 mmol/l (108mg/dl) and an SD of around 2.0 (36), and an HbA1C of 5.4. Having the SD target of one third of the blood glucose average gives me a very valuable goal. I’d like to get the SD a little lower. When continuous glucose monitoring gets a little more reliable/robust/usable/cost effective/subsidised in this country, then I expect it will be the tool that lets me effectively reduce my SD further. I’m conscious that reducing my carbohydrate consumption might also help.
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