Journal of Diabetes & Metabolism

A Comparative Study of Waist Hip Ratio and Body Mass Index (BMI) in Diabetic and Non Diabetic Individuals of Chitwan, Nepal

Bishal Joshi^* and Laxmi Shrestha ^*Correspondence: Bishal Joshi, Assistant Professor, Department of Physiology, Universal College of Medical Sciences, Nepal, Tel: +9779804412334; 9779845209783, Email:

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Introduction

Diabetes mellitus (DM) comprises a group of common metabolic disorders that share the phenotype of hyperglycemia. Several distinct types of DM exist and are caused by a complex interaction of genetics, environmental factors, and life style choices. Diabetes mellitus (DM) is a condition with heterogeneous group of syndromes characterized by impaired carbohydrate, fat and protein metabolism. It results from either lack of insulin secretion or decreased sensitivity of the tissues to insulin [1,2]. Type 1 DM results from autoimmune beta cell destruction, which leads to insulin deficiency. Type 2 DM is a heterogeneous group of disorders characterized by variable degrees of insulin resistance, impaired insulin secretion, and increased glucose production [3]. The incidence of type 2 DM is rapidly increasing worldwide and constitutes a major global health problem [4]. The various risk factors for the development of type 2 DM are obesity, ethnicity, sedentary life style, sex, family history, hypertension and smoking. However, there is now overwhelming evidence from experimental, epidemiological and interventional studies that obesity is a major risk factor for Type 2 DM among all risk factors [5]. The Nepal Diabetes Association (NDA) report says that among people aged 20 years and older living in urban areas, 15% are affected by this disease. Among people aged 40 years and older in urban areas, this number increased up to 19% [6].

Overweight and obesity are defined as abnormal or excessive fat accumulation that may impair health. Diabetes mellitus (DM) and obesity have a complex relationship with type 2 diabetes strongly associated with obesity [7]. Obesity, particularly visceral or central (as evidenced by the waist circumference and waist-hip ratio) is very common in type 2 DM [3]. From the clinical perspective, visceral adipose tissue is known to generate diabetogenic substances and may provide more information than total fat for diagnostic evaluation than generalized body fat [8]. Waist circumference and waist/hip ratio have been used as measures of central obesity (where visceral adipose tissue is stored), and body mass index (kg/m²) has been used as a measure of general obesity [9].

Obesity is now a global problem and the enormous implications for diabetes of this problem are now clear [10,11]. Obesity with an abdominal fat distribution probably accounts for 80-90% of all patients with type-2 diabetes mellitus [12]. Plethora of studies have shown a strong association between excess weight and risk of incident diabetes. Therefore, this study is designed to see the relationship of central and generalized obesities with type 2 diabetes mellitus in Chitwan district of Nepal.

Material and Methods

Study site and duration

The present study was conducted at College of Medical Sciences- Teaching Hospital, Bharatpur. The duration of the study was one year, i.e., from September 2013 to September 2014. The samples were selected from the patients visiting the OPD with confirmed diagnosis of Type-2 Diabetes Mellitus.

Selection of data

This is a comparative study of 200 participants. There are 100 participants with confirmed diagnosis of type 2 DM and 100 participants without any history of type 2 DM. Subjects with age group >35 years were selected for the study.

For estimation of sample size, initially pilot study was done by taking 20 participants for calculation of body mass index. In this study standard deviation for BMI was found 2.96. This was used to calculate the sample size by using following formula.

N= (r+1)/r*σ² * (Zβ+Zα)² /d²

N=no of participants

r =ration of control to case. (For equal no of case and control r =1)

σ=standard deviation (from pilot study)

Zβ=power of test at 80%=0.84

Zα=level of significance (1.95 at 5%)

d =expected mean difference between case and control (d=1.2)

From above formula number of participants (N) was 95.40. So we selected the sample size of 100 participants in diabetic and 100 participants in control group.

Control group include the people who are self-reported cases of non-diabetics and who do not show any classical sign and symptoms of diabetes mellitus. Control population was chosen from same hospital which consisted of the individuals visiting the hospitals for routine check-ups, visitors of the ward patients and non-teaching staffs.

Inclusion criteria

Subjects (>35 years of age) visiting the OPD and admitted in IPD with confirmed diagnosis of Type-2 Diabetes Mellitus.

Diagnosis of DM was made according to the following criteria (set by the WHO):

• Symptoms of diabetes plus random blood glucose concentration ≥ 200 mg/dL, or

• Fasting blood glucose ≥ 126 mg/dL, or

• Glycated hemoglobin (HbA1C) >6.5%, or

• Two hour blood glucose ≥ 200 mg/dL during an oral glucose tolerance test.

Exclusion criteria

• Patient with serious illness,

• Other specific types of Diabetes Mellitus

• Other causes of abdominal distension

• Pregnancy

• Study participants who are not willing to participate in the study.

Procedure

Subject with known case of diabetes mellitus type 2 were chosen as the case and their laboratory reports were obtained for confirmation. After that detailed history of study participants were taken and finally following anthropometric measurements were done.

• Weight in kg

• Height in cm

• Waist circumference in cm

• Hip circumference in cm

Weight was measured using portable weighing machine. Height was measured using calibrated stadeometer. Height of the subject was measured without shoes in cm and then converted to meter and weight was taken in kilograms.

Waist and hip circumference were measured as per the WHO guidelines [13].

• Waist and hip circumference were measured with a nonstretchable tape. Measurement was taken at standing position and bulky clothing was avoided.

• Waist circumference was measured at the approximate midpoint between the lower margins of last palpebral rib and the top of iliac crest in the mid-axillary line at the end of normal expiration.

• Hip circumference measurement was taken around the widest point of buttocks.

• Both measurements were taken with a stretch resistant tape wrapping snugly around the subject keeping the tape level parallel to the floor at the point of measurement.

With the above obtained data following parameters were calculated (Table 1):

Table 1: Classification of BMI according to WHO criteria and “Asian Criteria [14].

1. Body mass index

2. Waist hip ratio

Statistical analysis

Statistical analysis was done using SPSS 20.0 version (Statistical Package for Social Science for Windows Version) and Microsoft Office Excel 2010. Results on continuous measurements were presented as Mean ± SD and results on categorical measurement were presented in Number and Percentage (%). Student ’ s Independent t-test and p-values associated with it were used to confirm the statistical validity of the obtained descriptive statistics. Comparison was done at 95% confidence interval of the distribution of the data and p<0.05 was considered as level of significance.

Results

As shown in Table 2 total 200 participants were included in the study and out of them 100 (50%) were diabetic and 100 (50%) were non-diabetic. In diabetic participants 53 were male and 47 were female. In non-diabetic participants 49 were male and 51 were female. As shown in Table 3, the range of age for male, female and total participants was 55.48 ± 11.294, 55.88 ± 11.284 and 55.19 ± 11.265 years respectively. The range of age for male diabetic and non-diabetic participants was 56.40 ± 11.086 and 54.49 ± 11.547 years respectively. Likewise the range of age in female diabetic and non-diabetic participants was found to be 56.06 ± 11.805 and 53.78 ± 10.782 years respectively.

Table 2: Gender-wise distribution of study participants.

Table 3: Comparison of study participants on the basis of Age (Years).

The range of BMI for male, female and total participants was 23.79 ± 2.564 kg/m², 24.55 ± 3.380 kg/m² and 24.16 ± 3.009 kg/m² respectively. Likewise for male diabetic and non-diabetic participants range of BMI was 24.35 ± 3.135 kg/m² and 23.18 ± 1.569 kg/m² and for female diabetic and non-diabetic participants, range of BMI was 25.20 ± 4.063 kg/m² and 23.95 ± 2.495 kg/m² respectively. As shown in the Table 4 and Figure 1 the mean Body Mass Index of total diabetic patients was higher than of non-diabetic participants and it was statistically significant (p=0.005). Similarly BMI of male diabetic participants was higher than male non-diabetic participants and the difference was significant (p=0.021). However the difference was not statistically significant for females (p=0.067).

Table 4: Comparison of study participants on the basis of body mass index (BMI).

Figure 1: Error bar showing comparison of body mass index of male and female diabetic and non-diabetic participants.

The reference range of WC for male, female and total subjects was 89.86 ± 6.603 cm, 85.96 ± 7.112 cm and 87.95 ± 7.114 cm respectively. Likewise in male diabetic and non-diabetic participants, range of WC was 91.90 ± 7.381 cm and 87.66 ± 4.816 cm and for female diabetic and non-diabetic participants, range of WC was 87.86 ± 8.712 cm and 84.21 ± 4.669 cm respectively. As shown in Table 5 and Figure 2 the mean waist circumference of the total diabetic patients was higher than that of non-diabetic participants and the difference was statistically significant (p=0.000). Similarly in male participants WC of diabetics was higher non-diabetics and the difference was statistically significant (p=0.001) and in female participants also WC of diabetics was higher non-diabetics and the difference was statistically significant (p=0.011).

Table 5: Comparison of study participants on the basis of waist circumference (WC).

Figure 2: Error bar comparing mean waist circumference of male and female diabetic and non-diabetic individual.

The reference range of WHR for male, female and total subjects was found to be 0.961 ± 0.047, 0.886 ± 0.054 and 0.924 ± 0.063 respectively. Similarly range of WHR in male diabetic and nondiabetic participants was found to be 0.994 ± 0.031 and 0.926 ± 0.034 and female diabetic and non-diabetic participants was found to be 0.922 ± 0.046 and 0.853 ± 0.037. As shown in the Table 6 and Figure 3 the mean waist hip ratio of the total diabetic patients was higher than of non-diabetic participants and the difference was statistically significant (p=0.000). Similar results were obtained for male (p=0.000) and female (p=0.00) participants separately.

Table 6: Comparison of study participants on the basis of waist hip ratio.

Figure 3: Error bar comparing mean waist hip ratio of male and female diabetic and non-diabetic individual.

Discussion

Increase in obesity is one of the serious health problems in the present world as it is proportional to the rate of development of diabetes mellitus and cardiovascular diseases. In our study we tried to find the association of anthropometric measurements like waist hip ratio and body mass index with type 2 diabetes mellitus in the people of Chitwan [14].

In the present study a total of 200 participants were included. Out of them 100 were diabetic and 100 were non-diabetic. Gender-wise distribution of the diabetic population comprised of 53% male participants and 47% female participants (Table 1) whereas non-diabetic participants consisted of 49% male and 51% female participants (Table 1).

In present study the BMI range of the diabetic male (24.35 ± 3.135 kg/m²) was higher than non-diabetic males (23.18 ± 1.569 kg/m²) and the result was statistically significant (p=0.021). Likewise in case of diabetic females BMI range (25.20 ± 4.063 kg/m²) was slightly higher than non-diabetic females (23.95 ± 2.495 kg/m²) but the comparison was not statistically significant (p=0.067). But the total BMI of both male and female of diabetic participants (24.75 ± 3.607 kg/m²) was significantly higher (p=0.005) than non-diabetic participants (23.58 ± 2.117 kg/m²). These results indicate that the risk of developing diabetes is certainly higher among male with increasing BMI but it also indicates that the female subjects and diabetic status may be independent with respect to the variation of body mass index.

In a similar study in Pakistan Ali et al. [15] found that mean WC, WHR and BMI were higher in both male and female diabetic participants than non diabetics. In a similar cohort study Wei et al. on Mexican Americans concluded that weight, BMI, waist circumferences, and waist-to-hip ratio positively predict Type 2 diabetes independent of age and sex [16]. Similarly Patel et al. [17] in a comparative study found that cut off point of BMI was higher for diabetic than non-diabetics which is in consistent with present study. Likewise in a similar study done in a tertiary care centre of Nepal, Ranabhat et al. [18] found that BMI and WC of diabetic individuals were higher than non diabetics. However the findings of present study slightly contradict with study of Shah et al. [19] in Kavre district of Nepal as they found BMI of diabetic females (23.07 ± 6.7 kg/m²) was slightly lower than the non-diabetics females (23.15 ± 10.4 kg/m²) but in their study BMI was higher for diabetic males (24.32 ± 7.0 kg/m²) than non-diabetic males (22.07 ± 7.4 kg/m²) which was similar to the present study. Similarly result of present study was also consistent with the study of Quio et al. [20] and Vazquez et al. [21]. So these studies strongly support the conclusion of the present study that increases in BMI has direct correlation with DM type 2.

In present study mean waist circumference of the total diabetic participants (90.00 ± 8.246 cm) was higher than that of nondiabetic participants (85.90 ± 5.025 cm) and the difference was statistically highly significant (p=0.000). Similarly waist circumference of male diabetic participants was significantly higher than male nondiabetic participants (91.90 ± 7.381 cm vs 87.66 ± 4.816 cm; p=0.001). Likewise waist circumference of female diabetic participants was significantly higher than female non diabetic participants (87.86 ± 8.712 cm vs. 84.21 ± 4.669 cm; p=0.11). These results indicate that the risk of developing diabetes is certainly higher among male subjects with waist circumference 91.9 cm or above and among female subjects 87.8 cm or above. Nonetheless, it also points out by the combined analysis of both male and female diabetic subjects that waist circumference higher than 90 cm might be the risk factor for both the sexes.

Plethora of studies has demonstrated that individuals with type 2 diabetes have greater waist circumference than non-diabetics [22,23]. The result of present study in case of male subjects is corroborated by the study of Shah et al. [5] but in contrast to present study their study indicates that the female and diabetic status may be independent with respect to the variation of waist circumference. However in a similar study Patel et al. [17] conclude that the risk of developing type 2 DM for male subjects maximized with WC >98 cm. Similarly Humayun et al. [24] in their study concluded that the trend of diabetes increases with increase in the BMI and WC.

In present study waist hip ratio of the total diabetic patients (0.960 ± 0.053) was higher than of non-diabetic participants (0.889 ± 0.051) and the difference was statistically significant (p=0.000). Similarly WHR ratio of male diabetic participants (0.994 ± 0.031) was higher than male non diabetic participants (0.926 ± 0.034). Likewise waist hip ratio was higher in female diabetic participants (0.922 ± 0.046) than female non diabetic participant (0.853 ± 0.037). Again in both cases result was statistically highly significant (p=0.000 in both cases). These results indicate that the risk of developing diabetes is certainly higher among male and female diabetics than non-diabetic participants as WHR, the marker of central obesity is significantly higher in diabetics than non-diabetic participants.

So the result of comparison of WHR was highly supported by another similar study in Nepal [5] as they found that WHR of the diabetic male and females participants was significantly higher than the non-diabetic male and female participants. Similar studies by Qiao [20] and Wang et al. [22] also concluded that WHR was significantly higher in diabetic individuals than non-diabetics and WHR was associated with type 2 diabetes independently. A possible pathophysiological explanation is that excess intra-abdominal adiposity may have the potential to influence metabolism through alterations in the secretion of adipokines [25]. Previous studies have also reported that larger thigh and hip circumferences are associated with better glucose tolerance and an inverse relationship exists between increasing hip circumference and diabetes [26].

In present study WC cut off point for male 90 cm or above and for female 85.5 cm or above was found to be the risk for developing Type 2 DM. Lean et al. [27] suggested that a waist circumference of 94 cm for men and of 80 cm for women should be considered the cut off for limiting weight gain, whereas 102 cm for men and 88 cm for women should be considered for reducing weight. The WC cut off levels for female found in this study was higher than cut off for limiting weight gaining (80 cm). This suggests that there is need for increasing the awareness in females of this area toward their higher weight. The cut off point for female WC was almost similar (85 cm) with the result of shah et al. [16] observed in Kavre district of Nepal but in present study cut off point in case of male was higher than observation of their study (87 cm). This may be due to cultural differences and difference in life style among the people living in different regions of Nepal. This present study contradicts with the reflection of Łopatyńskiet et al. [28] as they found cut off point of WC for male to be 99 cm and 97 cm for female. This difference may be due to the ethnic variation.

In present study cut off point for WHR was 0.96 for male and 0.88 for female. WHO included a high WHR defined as a ratio >0.90 in men and >0.80 in women as a criterion for diagnosing the metabolic risks in south Asians. Snehalatha et al. [29] in their study on Asian Indian adults found that cut off WHR for male and female was 0.88 and 0.81 respectively which is low in comparison to present study. Shah et al. [16] in their study found WHR cut off points 0.96 and 0.87 for both male and female respectively which is quite consistent with the present study.

These results indicate that Nepalese population has higher WHR compared to other south Asian as well as Asian Indian population and hence pose a greater risk for development of type 2 diabetes mellitus.

Conclusion

The present study concludes that Body mass index, waist circumference and waist hip ratio all were higher in diabetic participants in comparison to non-diabetic participants. Further longitudinal study should be designed in high risk groups that would aid in better understanding the relationship of anthropometric parameters with type 2 diabetes mellitus.

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