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Prevalence of Metabolically Unhealthy Normal Weight and Its Influence on the Risk of Diabetes
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This longitudinal study assessed the association between the presence of metabolic syndrome components in individuals with normal weight and the risk for diabetes over a mean follow-up duration of 3.1 years. In an adjusted model, the presence of at least one metabolic syndrome component in an individual with normal weight was associated with a three times higher risk for diabetes compared with individuals with no components of metabolic syndrome. The presence of each additional metabolic syndrome equivalent was associated with a higher risk for diabetes (two components present: HR, 8; three components present: HR, 12).
- The presence of metabolic syndrome components in individuals with normal weight was associated with an increased risk for incident diabetes.
abstract
This abstract is available on the publisher's site.
Access this abstract nowAIMS
To conduct the first nationally representative study on epidemiological data of metabolically unhealthy normal weight (MUNW) focused only on non-diabetic subjects and determine the predictive effect on diabetes in China.
MATERIALS AND METHODS
A longitudinal study was conducted using data from the Rich Healthcare Group in China. The metabolic status was determined by the revised NCEP ATP III criteria, and individuals with two or more criteria were categorized as MUNW and diagnosed with metabolic syndrome (MetS) if they met three or more.
RESULTS
Of a total of 63,830 non-diabetic normal-weight individuals, 8,935 (14.0%) were classified as MUNW and 1,916 (3.00%) were diagnosed with MetS. After adjusting for potential confounders, individuals with MUNW had a greater diabetes risk (4.234 [95% CI: 3.089,5.803]) than those without MUNW during an average of 3.10 years of follow-up. Also, the multivariable-adjusted HRs for developing diabetes were 3.069 (95% CI: 1.790,5.263), 7.990 (95% CI: 4.668,13.677), 11.950 (95% CI: 6.618,21.579) for participants with one, two, and three or more components, respectively, compared to those without any components. Further analyses suggested that the number of MetS components present is associated with the risk of diabetes, especially in metabolically unhealthy normal-weight young male adults. Multivariable-adjusted hazard ratios (95% CI) for incident diabetes among individuals with one, two, and at least three components were 4.45 (1.45, 13.72), 9.82 (3.05, 31.64), and 15.13 (3.70, 61.84) for participants aged ≤44 years, 3.55 (1.81, 6.97), 8.52 (4.34, 16.73), and 13.69 (6.51, 28.77) for male participants, respectively.
CONCLUSIONS
The prevalence of MUNW is 14% in Chinese normal-weight non-diabetic individuals, and active intervention is necessary for this category of people. The presence of MUNW significantly increases the risk of diabetes, and the risk of diabetes is associated with the number of MetS components present in the patient.
Additional Info
The prevalence of metabolically unhealthy normal weight and its influence on the risk of diabetes
J. Clin. Endocrinol. Metab. 2023 Mar 14;[EPub Ahead of Print], J Ye, K Guo, X Li, L Yang, Z ZhouFrom MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine.
Management strategies for individuals with metabolically unhealthy normal weight - The need of the hour
There has been a rising prevalence of diabetes in the normal-weight adult population with abnormal metabolic parameters.1 Although this entity of metabolic obesity has existed since it was first described in 1980 by Rudermann et al, various studies have reported a prevalence varying from 5 to 45% due to ethnic and geographic differences. Ye et al have done a population-based retrospective study from an existing database of 63,830 individuals who were >20 years old and had normal BMI.2 All individuals who reported for a health check at least twice between 2010 and 2016 were screened for metabolic risk factors such as BMI, fasting plasma glucose, serum triglycerides, total cholesterol, LDL cholesterol, and HDL cholesterol. Those with more than two risk factors were classified as metabolically unhealthy normal-weight (MUNW) individuals, and those with more than three were classified were diagnosed with metabolic syndrome. The sample population was large and included people from various provinces of China and matched for risk factors like age, gender, alcohol, BMI, smoking, and family history.
The study found that the prevalence of MUNW was 14% (8935 subjects) and that of Metabolic syndrome was 3% (1916 subjects). Multivariable-adjusted hazard ratios for diabetes were 3.069, 7.990, and 11.950 for one, two, and three risk factors, respectively. A limitation of the study was that the diagnosis of diabetes was based on either a FPG >7 mmol/L or self-reported diabetes, which could have been erroneous considering the large sample size. The study reported that the incidence rate of new diabetes was higher in the elderly (>60 years) group and lower in the younger (<44 years) group, whereas the risk of diabetes with each component of metabolic syndrome as per NCEP ATP III was higher in the <44 years, attributing the same to poorer compliance to MNT and lifestyle changes.
Prevalence of MUNW/MONW in Asian countries in various studies has shown a prevalence varying between 12 and 30%.3
Study
Year
Region
Population
Diabetes
Prevalence
H. He et al
2019
China
2654
729
27.46
A. Jia et al
2018
China
15291
1771
11.58
Kapoor et al
2020
India
1147
364
31.43
Kim et al
2014
Korea
12217
1575
12.89
Kim et al
2018
Korea
3949
868
21.98
Schee Kim et al
2015
Korea
2078
283
13.61
H. Zhao et al
2012
China
407
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This study found an age- and gender-matched risk of diabetes of 4.234 at the 3-year follow up. The numbers of patients with diabetes diagnosed during follow-up were 73 (0.22%), 208 (0.97%), 255 (3.63%), and 182 (9.50%) for participants with zero, one, two, and at least three components at baseline, respectively. The cumulative incidence of diabetes comes to 714 patients (8%).
This is in variance with other studies as mentioned below.
A recent meta-analysis by Rakhmat et al of various studies in Asian populations done by various groups revealed an OR of 1.6 for developing diabetes among people with MUNW.4 The prevalence of diabetes in NWO was 19.7% in a regional population-based study done in the southern state of Kerala.5
This study by Ye et al has established the role of having a lower normal BMI in youth. This study highlights the importance of screening <44 years of age for metabolic risk factors and subject those with more than two risk factors to intensive lifestyle modifications and do primary prevention of diabetes at a risk factor level instead of diagnosing at fasting hyperglycaemia or elevated HbA1c level. Further prospective studies are needed to study the impact of lifestyle and medical treatment on individuals with MUNW to further justify screening and intervening individuals with this phenotype.6
References
Type 2 diabetes (T2D) has conventionally been considered as a disease of overweight and obesity. However, studies from different parts of the world (particularly India) have shown that even an individual with normal or low BMI can present with T2D. In this study, Ye et al explore the concept of metabolically unhealthy normal weight (MUNW) in a large, nationally representative database from China, and analyse the risk of development of T2D in MUNW individuals, as well as those with metabolic syndrome (MetS). Compared with metabolically healthy individuals, both MUNW and MetS individuals had a significantly higher risk of developing T2D. The risk increased with the number of components of MetS present, and was particularly high among young males. The study has important implications. Many of the currently available algorithms for assessing the risk of diabetes utilise BMI as a risk factor. In populations with high prevalence of MUNW, such an approach would miss a significant proportion of at-risk individuals. Similarly, some of the latest therapies that focus on weight reduction may not be ideal for MUNW individuals with T2D. Utilisation of more precise markers of abdominal obesity (such as waist circumference) and looking for components of MetS even in normal weight individuals will help in detection of MUNW individuals. Further research is warranted into the pathophysiology of T2D in MUNW so that more focused and effective therapeutic modalities can be developed.