Metabolic syndrome does not increase the risk of conversion of impaired glucose tolerance to diabetes in Asian Indians—Result of Indian diabetes prevention programme

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Abstract

Aims

In this study, we assessed for the prevalence of metabolic syndrome (MetS) in the cohort of subjects with impaired glucose tolerance (IGT) in the Indian Diabetes Prevention Programme and studied whether the syndrome enhanced the conversion to diabetes.

Methods

Effectiveness of lifestyle modification (LSM), metformin (Met) and LSM plus Met was tested in a randomised, controlled primary prevention study in subjects with IGT n = 502 (M:W 397:105) at a median follow up of 30 months. Baseline prevalence of MetS was calculated using the WHO criteria. Insulin resistance (IR) was calculated using homeostasis model assessment (HOMA) method.

Results

MetS was present in 233 subjects (46.4%; 95% CI 41.9–50.9) in the total group, in men (n = 168; 42.3%; 95% CI 37.4–47.3) and in women (n = 65; 61.9%; 95% CI 51.9–71.2) (men versus women χ2 = 12.8, p = 0.0005). Insulin resistance (HOMA-IR  4.1) was present in 69.1% with no gender difference. IR increased proportionately with increasing number of abnormalities, in IGT (39.8%), IGT plus one abnormality (56.5%) and IGT plus any two or more abnormalities (69.1%) (Mantel Haenszel χ2 = 22.8, p < 0.0001). Incidence of diabetes was similar in subjects with (40.3%) (n = 94/233) or without (40.1%) (n = 108/269) MetS (p = 0.97). Cox's regression analysis confirmed that MetS did not enhance the conversion rate of IGT to diabetes both in the control (HR = 0.88, 95% CI 0.53–1.47, p = 0.63) and in the total group (HR = 1.02, 95% CI 0.78–1.35, p = 0.88), after correcting for effects of intervention.

Conclusion

Prevalence of MetS is high in Asian Indian IGT subjects, especially in women. However, it did not influence the rate of conversion of IGT to diabetes.

Introduction

Metabolic syndrome (MetS) consists of a cluster of risk factors, which show strong association with diabetes and cardiovascular disease [1], [2], [3]. Asian Indians living in native or immigrant countries show equally high risk of both the disorders relative to many other races [4], [5], [6]. The higher risk is not accounted for by a higher prevalence of the conventional risk factors [4]. It is probably related to a combination of higher genetic or ethnic susceptibility and lower thresholds for the risk factors, as demonstrated in several epidemiological studies by our centre [7]. Prevalences of MetS [8] and impaired glucose tolerance (IGT) are high in Asian Indians [9]. The risk of conversion to diabetes may be increased by the coexistence of MetS [2], [3].

In a recent prospective study on primary prevention of diabetes, in native Asian Indians, we observed a high conversion rate of persistent IGT (IGT on two OGTT) to diabetes (>18.0%) [10]. The conversion rate was significantly reduced by life style modification (LSM) or metformin (Met) [10]. A secondary analysis was done to find out the prevalence of MetS in this cohort of persistent IGT and also to see if MetS influenced the rate of conversion to diabetes.

Section snippets

Subjects and methods

A community based prospective study was carried out to find out the feasibility of primary prevention of diabetes in Asian Indian subjects with persistent IGT [10].

The effectiveness of LSM or Met or LSM plus Met was tested in 502 (M:W 397:105) of 531 subjects who completed a median follow up of 30 months. Non-diabetic subjects with no major illness aged 35–55 years were recruited from the middle-class population working in service organizations and also from their families. A total of 10,839

Statistical procedures

Mean and standard deviation (S.D.) are shown. Group comparisons were done using unpaired Students t-test, ANOVA or by chi-square test as appropriate. The conversion rate at a median follow up of 30 months was computed using the Cox's regression equation both in the control and in the total group after adjusting for age and sex. The influence of MetS on the conversion rate was calculated after adjusting for the effects of intervention measures (intervention yes/no). p value of <0.05 was

Results

Table 1 shows the prevalence of abnormalities and the mean values of insulin resistance in the respective groups. MetS was seen in 233 subjects (46.4%; 95% confidence interval (CI) 41.9–50.9) in the total group, in men (n = 168; 42.3%, 95% CI 37.4–47.3) and in women (n = 65; 61.9%, 95% CI 51.9–71.2). (Men versus women, χ2 = 12.8, p = 0.0005).

IGT without any other abnormality was less common than in combination with other abnormalities. The clustering was more common in women than in men. Prevalence of

Conclusion

In the IDPP cohort of IGT subjects we found a high prevalence of MetS. However, the presence of the syndrome did not increase the incidence of diabetes in the total group after correcting for the effect of intervention.

Several studies had shown that presence of MetS was predictive of future diabetes [1], [2], [3]. Recently a Chinese study showed no significant association of MetS in the development of type 2 diabetes [13]. It showed that obesity rather than other features of MetS predicted the

Acknowledgements

We thank the study subjects for their participation in the study. We also thank the epidemiology field staff including Dr. Bhaskar AD, Mrs. Mary Simon, Mr. C.K. Sathish, Mr. S. Selvam, Mr. M. Muruganandham, Mrs. A. Catherin Seeli, Mrs. V. Lalitha Manjula and Ms. L Subhashini for the efficient conduct of the study. Secretarial assistance of Ms. Subhaa K is acknowledged.

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