We have discussed extensively over the past six years the
nexus between Obesity, Type 2 Diabetes and now mortality. In a recent study by
Tobias et al in NEJM there is an assumed nexus between obesity, as determined
by BMI, and the impact of the combo on mortality.
Tobias et al conclude:
We observed a J-shaped association between BMI and
mortality among all participants and among those who had ever smoked and a
direct linear relationship among those who had never smoked. We found no
evidence of lower mortality among patients with diabetes who were overweight or
obese at diagnosis, as compared with their normal-weight counterparts, or of an
obesity paradox.
Namely, the greater the BMI the greater the chance of death.
On the other hand amongst those who did not smoke there was the interesting
anomaly that mortality increased at BMI below 22.5. One often wonders what this
is due to and it is common across other morbidities.
The authors continue:
Our findings with respect to the relationship between BMI
and mortality due to specific causes are consistent with those of prior studies
conducted in the general population. Among participants who had never smoked, the
relationship of BMI to both cardiovascular mortality and cancer mortality
appeared to be monotonic and linear. No significant association was observed
between any BMI category and the risk of death from cardiovascular disease among
participants who had ever smoked; however, participants in the lowest BMI
category who had ever smoked had a significantly elevated risk of death from
cancer.
Proposed biologic mechanisms of the alleged obesity
paradox include an increased genetic influence and more severe diabetes among normal-weight
persons with diabetes or the effect of a “metabolically obese normal weight” phenotype.
However, normal-weight participants in our cohort were no more likely to report
diabetes symptoms or coexisting chronic diseases or to require insulin than
were overweight or obese participants. In contrast, normal- weight participants
were more likely to be smokers and to have lost weight before a diagnosis of
diabetes. Comparisons with this heterogeneous normal-weight group may therefore
underestimate the risk of death among the overweight and obese.
Smoking is a co-morbidity state. However the overall impact
of lifestyle choices must be considered more extensively amongst insurance
providers. Obesity is not a pre-existing condition nor is being a smoker. They
are life style choices. As such they should be assigned related risks.
Reference
Tobias, D., et al, Body-Mass Index and Mortality among
Adults with Incident Type 2 Diabetes, NEJM, 370; 3, Jan 2014. http://www.nejm.org/doi/pdf/10.1056/NEJMoa1304501
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