Monday, July 29, 2019

Retrospective #163: So, you think you’re just Pre-diabetic?

This lede in a story in USAToday sets the stage: “Higher blood sugar levels, even those well short of diabetes, seem to raise the risk of developing dementia, a major new study finds. Researchers say it suggests a novel way to try to prevent Alzheimer’s disease -- by keeping glucose at a healthy level” (my emphases). The article was based on a study at the University of Washington, Seattle, and was published in the New England Journal of Medicine.
MedScape Medical News quotes the study’s lead author, saying, “We considered blood glucose levels far into the normal (nondiabetic) range, and even there found an association between higher glucose levels and dementia risk.” “He said the results suggest that the ‘clinical determination of diabetes/not diabetes may miss important associations still there for people who are categorized as not having diabetes’.” That would be the Pre-diabetic.
The Associated Press story quotes Dallas Anderson, a scientist at the National Institute on Aging, the federal agency that paid for the study: “It’s a nice clean pattern -- risk rises as blood sugar does,” Anderson said. “This is part of a larger picture” and “adds evidence that exercising and controlling blood pressure, blood sugar and cholesterol are a viable way to delay or prevent dementia.” The ubiquitous triad: “…blood pressure, blood sugar, and cholesterol.”
The story also quotes a Dr. Crane: “At least for diabetics, the results suggest that good blood-sugar control is important for cognition.” And, for those without diabetes, he said, “It changes how we think about thresholds, how we think about what is normal, what is abnormal.” Is Dr. Crane saying that Pre-diabetic is abnormal? I think he is.
The Gupta Guide at MedPageToday commented, “Nondiabetic patients who developed dementia had a mean blood glucose level of 115mg/dl in the preceding 5 years compared with 100mg/dl in similar patients who did not have dementia. “The higher levels were associated with almost a 20% increase in the hazard for dementia.”
The New York Times take on the story also quoted Dr. Crane: “We found a steadily increasing risk associated with ever-higher blood glucose levels, even in people who didn’t have diabetes. There’s no threshold, no place where the risk doesn’t go up any further or down any further.” The association with dementia kept climbing with higher blood sugar levels and, at the other end of the spectrum, continued to decrease with lover levels.
Another related article from MedPageToday ties blood sugar (A1c) levels to cognitive function NOW, not to the future risk of dementia. The group studied was a population of non-diabetics, aged 50 and up, with BMIs between 25 and 30. Their mean A1c was 5.8%, with a range from 4.3% to 6.5%. The researchers found that “each of the three cognition parameters evaluated was significantly associated with A1c levels…”
That article, “Blood Sugar Tied to Cognitive Function,” added, “‘Lifestyle strategies’ to achieve strict glucose control could prevent age-related cognitive decline, even in individuals with A1c levels currently considered normal…”
So, what’s the takeaway?  What does it mean to change “how we think about thresholds, how we think about what is normal, what is abnormal”? What is considered “normal”? And what is “Pre-diabetic”? From 1979 to 1997 the threshold for Type 2 was two consecutive visits with a fasting blood glucose of ≥140mg/dl. In 1997, the threshold for a diagnosis was changed to ≥126mg/dl, and in 2010 the ADA added A1c standards, with an A1c of 6.5% for diabetes (with a “treatment goal” of 7.0%!!!), and an A1Cs of 5.7--6.4% for Pre-diabetes.
Richard K. Bernstein, consider 5.7% to be a full-blown Type 2 diabetes. Another MD, Dr. Ralph DeFronzo, in his Banting lecture at the 2008 ADA convention, said that “By both pathophysiological and clinical standpoints, these Pre-diabetic individuals with IGT [Impaired Glucose Tolerance] should be considered to have Type 2 diabetes.”
Statistically, you are 7-10 years away from diabetes and your heart disease risk is already rising. It has been more than 20 years since the diabetes threshold has been revised. Shouldn’t it be revised again NOW, and shouldn’t we all adopt “‘lifestyle strategies’ to achieve strict glucose control” and thus potentially “prevent [CVD, pancreatic cancer, and] age-related cognitive decline, even in those individuals with A1c levels currently considered normal…?

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