The U.S. Centers for Disease Control (CDC) estimates that as many as 88 million American adults — more than one in three — have prediabetes. But what at first looks like a bona fide health crisis might not be one after all, according to a new study.
For the report, which has just been published online in JAMA Internal Medicine, the researchers identified 3,412 older adults who took part in an ongoing investigation called the Atherosclerosis Risk in Communities Study, or ARIC. Sponsored by the National Heart, Lung and Blood Institute, it’s an epidemiologic study conducted in four U.S. communities that was originally established to investigate the causes of atherosclerosis (often called hardening of the arteries) and how it varies according to various risk factors and by race, gender, location and date. Six out of ten of the subjects were women and 17% were Black. At the beginning of the study in 1987 to 1989, the participants ranged in age from 45 to 64; by the time the current study was launched, the age range was 70 to 91.
The researchers used two common measurements to determine which of the subjects had prediabetes. The first was elevated glycated hemoglobin, as measured by an HbA1c test, which measures average blood sugar for the preceding two or three months. The second test was a measurement as determined by impaired fasting glucose, a test that checks fasting blood sugar levels, which means not having anything to eat or drink for at least eight hours before the test. The researchers determined that 44% of the subjects had prediabetes according to the HbA1c test and 59% had prediabetes according to impaired fasting glucose (29% had both of these conditions).
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Researchers find low risk of diabetes progression
The subjects were followed up for more than six years, during which time they had regular physical examinations. During that period, fewer than one in ten (9%) of the HbA1c group went on to develop full-blown diabetes. However, even more subjects (13%) reverted to normal blood sugar levels. (About one in five — 19% — died during the follow-up period). The numbers were even better for the impaired fasting glucose group. Among them, nearly half (44%) reverted to normal blood sugar. Only 8% progressed to diabetes, while 16% died.
The overall impression of the study is that a diagnosis of prediabetes might not be as worrying as we once thought and perhaps older adults don’t require strenuous treatment for the condition. They might not even need medication. As the authors expressed it, “The findings of the current study support a focus on lifestyle improvement when feasible and safe, especially given the broader benefits of lifestyle modification beyond diabetes prevention. Given the low risk of diabetes progression in this study (especially relative to mortality risk), it is unlikely that pharmacologic intervention or other aggressive approaches to diabetes prevention in older age will provide large benefits and could have unintended harmful effects.” The harmful effects, they went on to say, might include “overdiagnosis, anxiety, and implications for insurance coverage.” They concluded: “…prediabetes in older age may not be a robust diagnostic entity for predicting diabetes progression.”
When the new study appeared in JAMA Internal Medicine, it was accompanied by a commentary from two physicians from the University of California San Francisco, Kenneth Lam, MD, and Sei Lee, MD, who titled their piece “Prediabetes — A Risk Factor Twice Removed.” They cautioned that although more studies need to be done, it well might be that “shifting the cutoffs for diagnosing diabetes in older adults would help us focus treatment on those older adults for whom diabetes is likely to result in symptomatic end-organ damage, while avoiding identifying many older adults for whom diabetes is unlikely to cause harm.” They added that, “for many older adults, new-onset diabetes will often be mild and asymptomatic and only one of many potentially life-threatening conditions.” The new study, they said, “shows that identifying prediabetes in older adults should be regarded as a low priority, as it rarely leads to incident diabetes or adverse outcomes. To ensure high-value care for older adults, we should focus our care and research on what matters most to older adults and deprioritize twice-removed risk factors, such as prediabetes.”
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