Irl Hirsch, MD, may not have coined the term "glycemic variability," but if it becomes the "Show Me the Money" of diabetes lingo, he will be the Cuba Gooding, Jr. who made it popular.
Glycemic variability—which is the excursion of blood glucose from low to high and back again—is rooted almost accidentally in the Diabetes Control and Complications Trial of 1993. During that trial, subgroups of people with identical A1C levels were identified and it was found that those receiving basal and meal-time insulin injections had a significantly less risk of retinopathy than those receiving just basal insulin. Hirsch, who is medical director at the University of Washington Diabetes Care Center, attributes this decreased complication risk to lower glycemic variability in the basal and meal-time insulin group.
"Cells don't like going up and down," Hirsch tells dLife. "Specifically, the cells that we see with diabetes-related complications."
Glycemic Variability and Oxidative Stress
In the May/June 2005 issue of Journal of Diabetes and its Complications, Dr. Hirsch published a theory on the importance of glycemic variability with Michael Brownlee, MD, professor of Diabetes Research at Albert Einstein College of Medicine in New York. In the article, Hirsch and Brownlee argue that research is beginning to support the theory that oxidative stress and fluctuating blood glucose levels go hand in hand. Hirsch and Brownlee wrote that, "…glucose variability, considered in combination with A1C, may be a more reliable indicator of blood glucose control and the risk for long-term complications than mean A1C alone,"
While A1C tells you of the three-month average of blood-glucose levels, Hirsch tells dLife that glycemic variability tells you about the "quality of the A1C."
Suggestions for Keeping Glycemic Variability in Line?
To reduce against glycemic-variability extremes, Hirsch highly recommends protecting yourself against blood-glucose spikes.
"… Even if you don't believe in the glycemic-variability concept, most people who see themselves spike over 300 mg/dl (16.66 mmol/l) know they need to do something differently, because they cannot believe that that spiking over 300 is a good thing."
Hirsch says the easiest way to keep glycemic variability in line is to take insulin prior to eating and give it time to work. He points out that today's rapid-acting insulins aren't really that rapid, so he advises taking Humalog, NovoLog or Apidra 10 to 15 minutes prior to a meal—and that is if the glucose is within target.
"By doing this, you are not going to have as big a spike as you would if you gave the insulin right away or if you give the insulin after eating, which a lot of people do."
For controlling glycemic variability, Hirsch also recommends , and Prandin. He adds that the only way to really know your glycemic variability is through frequent testing or by using real-time continuous sensing.
Glycemic Variability Awareness—How Long Until More People Catch On?
Are people with diabetes getting on the glycemic-variability bandwagon? It seems some are!
Kelly L. Close of San Francisco, California, has type 1 diabetes and is the editor-in-chief of diaTribe, a newsletter about diabetes.
"My last A1C was decent, but I'd love having fewer after-meal highs and fewer lows. I feel better without them, but my A1C doesn't tell me anything about this!"
Close adds that data summaries from her OmniPod tell her that the "quality" of her scores can be higher!
"My glycemic variability tells me when I need to improve my habits," she says, "A1C averages sort of leave out what people with diabetes should be careful to avoid – the highs and lows."
For more diabetes clinicians and patients to jump on the glycemic-variability bandwagon, Hirsch argues that better clinical trials need to undertaken.
"We do need to get a better message out about variability and hypos," says Hirsch. "But as far as variability and complications are concerned, until we have the controlled trials that definitively prove this, it's going be very difficult to convince a lot of people about its importance. My bottom-line conclusion is that the basic science data makes sense—that the ups and downs of glucose variability data are bad. But now we need prospective, randomized trials to prove it."
NOTE: The information is not intended to be a replacement or substitute for consultation with a qualified medical professional or for professional medical advice related to diabetes or another medical condition. Please contact your physician or medical professional with any questions and concerns about your medical condition.
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