R ecently I received an e-mail with the following question, and think it's worth some commentary: "I have type 2 diabetes and it's like a yo-yo. I'd like to know exactly what a good number is."
I've always had a simple answer to whether blood glucose (BG) numbers are "good" or "bad:" they are neither They are simply numbers: high, in the target range, or low, but there's no goodness (nor badness) in a number.
More important, to answer the question, are several hidden issues:
First, does the patient have proper technique to check their BG? Not only knowing how to calibrate and use the meter, but are they checking routinely before meals, or after meals (and if so, how long after eating), or both before and after? And how often?
And how big is the yo-yo effect? If the patient is occasionally checking after a big meal and comparing the value to what they get before meals, the "spread" will be a lot bigger than if they are only checking before meals.
Is the patient checking before breakfast, and finding that it's high compared to before other meals? That's probably due to the "dawn phenomenon," in which night-time release of other hormones can cause early-morning elevations of blood glucose levels.
Is the patient perchance on a diabetes program that includes varying insulin doses? If so, it's possible that the instructions provided to the patient about insulin adjustment are actually causing a roller-coaster effect, and if so, the insulin instructions need to be changed.
Is the patient on a stable meal plan, stable exercise program, and have stable stress levels? If any of these are changing from one moment to the next, it's no surprise that the BG levels would fluctuate.
Now, back to the question: where should the BG levels for someone with type 2 diabetes be? Well, ideally, you might think that all people with diabetes should be aiming for normal levels. But there's plenty of evidence that normalizing all BG levels is extremely difficult, and carries a risk of accidental hypoglycemia. That has to be balanced against the reverse observation: that elevated BG levels mean elevated risk of diabetes complications, including eye, kidney, and nervous system damage. So any pronouncement about where BG levels should be must be tempered with caution.
It's my feeling that all patients with diabetes should be treated to avoid numbers higher than 400, and to avoid numbers lower than 60: there's an increased risk of acute complications of nausea and vomiting, dehydration, and subsequent nasty things if BG levels are in the 400's -- and clearly the risk of hypoglycemia is dramatically elevated if BG levels are below 60. So there's a starting point for where to aim.
And the ultimate in BG control would probably be to keep almost all (maybe 90%) of before-meal BG levels between 70 and 100, and after-meal BG levels below 150. That's a goal that's pretty close to what non-diabetic patients might have. Is it possible? Sure, even if you have type 1 diabetes: if you are on an insulin pump or multiple insulin doses, testing 4-10 times a day, and motivated to continue doing so for a prolonged period of time. (The best example of motivators might be pregnancy: young women with type 1 diabetes who are planning pregnancy, or are pregnant, would be potential candidates for an ultra-tight diabetes control program aiming at numbers like these.)
But the overwhelming majority of people with diabetes will have targets someplace between these extremes. Exactly where to aim might depend on general health issues (for instance, there's some evidence, although controversial, that aiming too low increases risk for people with T2DM and cardiovascular disease), age (older folks are generally considered to have a higher risk of complications from hypoglycemia), and motivation, as well as knowledge of diabetes by the physician setting the targets.
Earlier, I touched very briefly on another issue in setting BG target levels: how often the target must be met. I don't think that perfection is possible: there are way too many factors influencing BG levels, some of which are controllable, but others are not. So I'm very willing to settle for hitting the target levels part of the time: maybe 90% of the time.
What if you are hitting your targets 100% of the time? Well, first of all, congratulations. But secondly, maybe you should consider challenging yourself to tightening up the targets. This has been called "graduated goal setting."
Graduated goal setting is a technique that I routinely encourage new patients with diabetes to use: initially aim for some very wide ranging targets, like getting BG levels between 300 and 100 50% of the time; when the patient is routinely able to hit these targets, then discussing with the patient what targets seem reasonable to use in the near future: perhaps aiming for between 80 and 250 75% of the time. At each step, the targets are reviewed against the actual performance, and if the targets are not being met, adjustments to the treatment plan are implemented (perhaps a bigger dose of pills, or adding a second pill); if the targets are being met, consideration to tightening the targets for the next period of time.
But at all times, no matter what targets are being used, BG numbers are either high, low, or within the target range: they are never good nor bad.