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Review
. 2018 Jun;42(3):179-187.
doi: 10.4093/dmj.2018.0055. Epub 2018 May 31.

The Evidence for an Obesity Paradox in Type 2 Diabetes Mellitus

Seung Jin Han  1 , Edward J Boyko  2
Affiliations
Review

The Evidence for an Obesity Paradox in Type 2 Diabetes Mellitus

Seung Jin Han et al. Diabetes Metab J. 2018 Jun.

Abstract

Although overweight/obesity is a major risk factor for the development of type 2 diabetes mellitus, there is increasing evidence that overweight or obese patients with type 2 diabetes mellitus experience lower mortality compared with patients of normal weight. This paradoxical finding, known as the "obesity paradox," occurs in other chronic diseases, and in type 2 diabetes mellitus is particularly perplexing given that lifestyle intervention with one goal being weight reduction is an important feature of the management of this condition. We summarize in this review the findings from clinical and epidemiologic studies that have investigated the association between overweight and obesity (usually assessed using body mass index [BMI]) and mortality in type 2 diabetes mellitus and discuss potential causes of the obesity paradox. We conclude that most studies show evidence of an obesity paradox, but important conflicting findings still exist. We also evaluate if potential bias might explain the obesity paradox in diabetes, including, for example, the presence of confounding factors, measurement error due to use of BMI as an index of obesity, and reverse causation.

Keywords: Bias; Body mass index; Diabetes mellitus, type 2; Epidemiology; Mortality; Obesity; Survival.

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Conflict of interest statement

No potential conflict of interest relevant to this article was reported.

Figures

Fig. 1
Fig. 1. The limitations of epidemiological studies and body mass index (BMI).
See this image and copyright information in PMC

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