Yesterday afternoon I started reading through some of the articles published in the media about the study. Most were short items that included the basics found in the original press release issued to alert the media about the study publication.
One in particular stood out however, the article at Fox News, Diabetes May Be Cause of Deaths Linked to Obesity, a reprint of the WebMD article. It opened simply, "Another wrinkle has been added to the debate over whether obesity is a major cause of early death. New research suggests that it is, but only in people who also have diabetes."
Such drama makes a good teaser to capture your attention to read further, but unless you read the full-text, you won't know the full context of the findings. That's because the media is spinning this as a controversy because the findings are contrary to our assumptions; when in fact the data is alarming and needs a bit more attention to the details.
For example, the WebMD article included, "The new findings are not likely to end the medical debate about whether obesity is a direct or indirect cause of early death. The issue made headlines a year ago last spring, when CDC researchers reported that the risk of obesity-related death was much lower than had been previously believed. Researchers also reported no increase in death risk among people who were overweight but not obese. The report was widely criticized, and a reanalysis of the same data by researchers from the Harvard School of Public Health showed a strong association between obesity and early mortality."
So, what is the data really?
What the researchers did was analyze data from 15,408 participants in the Atherosclerosis Risk in Communities (ARIC) study to assess outcomes in the cohort regarding the development of acute organ failure within three years of the baseline examination, in-hospital death while ill with acute organ failure, and death within three years from baseline in all subject and those who developed acute organ failure. At the baseline examination both BMI and the presence of diabetes were defined; so was acute organ failure.
This particular population included adults aged 44 to 66, and they were diverse:
- 29.9% had normal BMI (21 to 24);
- 39% had an overweight BMI (25 to 29); and
- 27.5% had an obese BMI (30+)
What the researchers learned was, at baseline those with a BMI of 30 or higher were more likely than those with a lower BMI to also have diabetes (22.4% versus 7.9%; p = greater than 0.01).
Where the data is very interesting, even alarming, is the incidence of diabetes.
Overall 11.9% (1,890 subjects) had diabetes. Those with diabetes were more likely to have a BMI of 30 or higher, with 52% of those diagnosed with diabetes also at a BMI of 30 or higher.
The distribution of diagnosed diabetes was:
- BMI less than 20 = 4.4% had diabetes
- BMI 20 - 24 = 4.9% had diabetes
- BMI 25 - 29 = 10% had diabetes
- BMI 30 or higher = 22.4% had diabetes
When we see the incidence of diabetes as related to BMI, it is much easier to understand why the results were what they were. Those with higher BMI also had a higher incidence of diabetes. In the cohort, almost one in four with a BMI greater than 30 had diabetes!
In the three years of follow-up, the risk of developing acute organ failure was similar across BMI - 0.9% of subjects with normal BMI, 0.8% of subjects with overweight BMI and 0.9% of subjects with obese BMI. This one piece of data is probably the most important in the findings - regardless of BMI, the risk of developing acute organ failure was virtually identical across the cohort. But, at the same time, again regardless of BMI, the strongest independent predictor of development of acute organ failure was the presence of diabetes - as a risk factor, it carried a three-fold risk (odds ratio 3.2; 95% CI 2.1 to 4.7). It didn't matter what a person weighed - what mattered was the presence of diabetes.
The numbers here speak for themselves, quite loudly I might add, that the risk of developing acute organ failure is very high in those who have diabetes.
In addition, the data speaks volumes about the risk of death.
All cause mortality was also significantly higher in those with diabetes (again, regardless of BMI) - with almost a three-fold risk compared with those who did not have diabetes (odds ratio 2.7; 95% CI 2.1 to 3.5) Over the course of three years, 5.4% of subject with diabetes died compared with 1.6% of subjects without diabetes.
This is the kind of finding where the reaction "any questions?" is rhetorical - the finding is so statistically significant and strongly points to the problem - diabetes; not simply body weight.
As the researchers noted in their discussion "the development of acute organ failure and death after acute organ failure is more related to the presence of [diabetes] DM than to an increased BMI...Our results do not support the contention that obesity itself is a risk factor for increased mortality in patients with acute organ failure...In addition, our findings did not confirm an increased mortality in overweight or obese critically ill patients without [diabetes] DM...Our findings suggest that [diabetes] DM and associated hyperglycemia with insulin resistance, rather than obesity itself, is responsible for the development of acute organ failure and subsequent adverse outcomes in this middle-aged US population...Results of this study indicate that the presence of [diabetes] DM, rather than an increased BMI, accounts for a higher risk of acute organ failure and associated mortality."
But these findings are not going to stop those firmly of the belief that body weight alone is most important. It doesn't matter than numerous studies keep finding that diabetes, hyperglycemia and elevated blood sugars (even at levels some consider "normal") are statistically significant predictors of chronic illness and premature death.
The bottom line from this study is clear in my view - diabetes is a killer in those who are normal weight, overweight and obese.
To simply assume and continue to perpetuate the myth that someone who is overweight or obese is at a higher risk for developing chronic illness or dying prematurely simply because they are overweight or obese is engaging in scare tactics to motivate change in diet and lifestyle in the population - noble cause, but for the wrong reason.
It's pretty clear that the risk of diabetes is significantly higher as weight increases, but weight alone, in this study, was not a predictor of developing acute organ failure or death - diabetes was.