Past blood glucose control is a better predictor of diabetes-related outcomes than current blood glucose control in people with type 2, showing the importance of good control over time, according to a new analysis published in the journal Diabetes Care.
Researchers at the University of Gothenburg in Sweden looked at data from the UK Prospective Diabetes Study (UKPDS), a large study that tracked people with diabetes over time. Specifically, they looked at how early improvements in participants’ A1C level (a measure of blood glucose control over several months) soon after a type 2 diabetes diagnosis and later improvements in A1C were both linked to certain outcomes, including heart attacks and death from all causes five to 20 years later, as noted in a Medscape article on the study.
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Participants with type 2 were recruited between 1977 and 1991, when they were between 25 and 65 years old. Those with a fasting glucose level between 108 mg/dl and 270 mg/dl were randomly assigned to control their blood glucose mainly through diet, or through an intensive-control strategy that involved treatment with a sulfonylurea, insulin, or metformin. At the time of the study, not many other diabetes drugs were available — and metformin hadn’t been approved yet in the United States, but it was available in Britain, where the study took place. After the main part of the study ended in 1997, participants were followed for another 10 years, during which they were no longer bound to follow the treatment strategy assigned in the study.
Early control linked to larger reductions in risk of certain complications
The researchers found that based on the glucose control seen in the two study groups, treating people to achieve a 1% lower A1C level at the time of diagnosis was linked to an 18.8% lower risk of death from all causes 10 to 15 years later. But when this A1C reduction was delayed by 10 years, it was linked to only a 2.7% risk of death from all causes during the same window of time. Similarly, a 1% A1C reduction soon after a diabetes diagnosis was linked to a 19.7% reduction in heart attacks 10 to 15 years later, but delaying this A1C reduction by 10 years reduced this heart attack risk by only 6.5%.
The researchers noted that other studies have found smaller cardiovascular benefits from reducing A1C levels in people with type 2 based on shorter time periods. The latest analysis shows that following people for a longer period of 10 to 15 years may result in a better sense of the cardiovascular benefits of improved blood glucose control — much larger benefits than some shorter studies have found.
“Early detection of diabetes and intensive glucose control from the time of diagnosis is essential to maximize reduction of the long-term risk of glycemic complications,” the researchers concluded, adding that the expansion of drug treatment options since the time of the study — including many that don’t carry the risk of hypoglycemia (low blood glucose) — makes this goal more achievable than ever before.