Ethnic disparities in the association of impaired fasting glucose with the 10-year cumulative incidence of type 2 diabetes

https://doi.org/10.1016/j.diabres.2013.10.014Get rights and content

Abstract

Aims

Evidence of ethnic disparities in the conversion of prediabetes to type 2 diabetes is scarce. We studied the association of impaired fasting glucose (IFG) and fasting plasma glucose (FPG) with the 10-year cumulative incidence of type 2 diabetes in three ethnic groups.

Methods

We analyzed data for 90 South-Asian Surinamese, 190 African-Surinamese, and 176 ethnic Dutch that were collected in the periods 2001–2003 and 2011–2012. We excluded those with type 2 diabetes or missing FPG data. We defined baseline IFG as FPG of 5.7–6.9 mmol/L. We defined type 2 diabetes at follow-up as FPG  7.0 mmol/L, HbA1c  48 mmol/mol (6.5%), or self-reported type 2 diabetes.

Results

10-Year cumulative incidences of type 2 diabetes were: South-Asian Surinamese, 18.9%; African-Surinamese, 13.7%; ethnic Dutch, 4.5% (p < 0.05). The adjusted association of baseline IFG and FPG with the 10-year cumulative incidence of type 2 diabetes was stronger for South-Asian Surinamese than for African-Surinamese and ethnic Dutch. The IFG (compared to normoglycaemia) ORs were 11.1 [3.0–40.8] for South-Asian Surinamese, 5.1 [2.0–13.3] for African-Surinamese, and 2.2 [0.5–10.1] for ethnic Dutch.

Conclusions

The 10-year cumulative incidence of type 2 diabetes was higher and associations with baseline IFG and FPG were stronger among South-Asian Surinamese and African-Surinamese than among ethnic Dutch. Our findings confirm the high risk of type 2 diabetes in South-Asians and suggest more rapid conversion in populations of South-Asian origin and (to a lesser extent) African origin than European origin.

Introduction

The prevalence of type 2 diabetes has grown to epidemic proportions in the last few decades [1], [2]. The burden of type 2 diabetes is expected to increase even further due to factors as aging, urbanization, and the increasing prevalence of physical inactivity and obesity [2].

Several studies have shown that the prevalence and incidence of type 2 diabetes differ between ethnic groups; in particular, people of South-Asian origin are disproportionally affected [3], [4], [5], [6], [7], [8], [9]. Not only is the prevalence higher, but type 2 diabetes also seems to develop at an earlier age among South Asians than among populations of European origin [4], [6]. Moreover, a high risk of type 2 diabetes and its related morbidity and mortality have been reported among populations of African origin [9].

Overt type 2 diabetes is often preceded by a condition known as prediabetes, which is characterized by increased glucose levels that are not high enough to justify the diagnosis of diabetes, yet hallmark the development of insulin resistance [10], [11]. According to the ADA guidelines, prediabetes can be classified as having impaired fasting glucose (IFG), impaired glucose tolerance (IGT), and/or a glycated hemoglobin A1c (HbA1c) level of 43–48 mmol/mol (5.7–6.5%) [11]. Although it has been stated that IFG and IGT should not be viewed as clinical entities in their own right, prediabetes is now widely recognized as a risk factor for type 2 diabetes and cardiovascular disease [11]. According to the ADA guidelines, patients with known prediabetes should be screened for type 2 diabetes every 1–2 years [11].

Despite the ethnic differences in the prevalence and incidence of type 2 diabetes, the knowledge about ethnic disparities in conversion from prediabetes to type 2 diabetes is limited to one study that has described a stronger association between prediabetes and incident type 2 diabetes among Hispanics than among non-Hispanic whites [12]. It is unknown whether there are disparities in conversion from prediabetes to type 2 diabetes between those of South-Asian, African, and European origins. Knowledge about such disparities may help to determine whether more frequent diabetes testing of those with prediabetes is warranted. It will also determine whether early interventions should be recommended in order to reduce the incidence of type 2 diabetes among these disproportionately affected groups. Therefore, we aimed to compare the associations of IFG and fasting plasma glucose (FPG) with the 10-year cumulative incidence of type 2 diabetes among Hindustani Surinamese (South-Asian origin), African Surinamese (African origin), and ethnic Dutch (European origin) living in the Netherlands.

Section snippets

Study population

The study population consisted of participants in the SUNSET study (Surinamese in the Netherlands: study on health and ethnicity). The SUNSET study was a cross-sectional study based on a random sample of 2975 Surinamese and ethnic Dutch individuals, aged 35–60, drawn from the population register of two neighborhoods in southeast Amsterdam, as previously described [3]. Almost half the population of the former Dutch colony of Surinam migrated to the Netherlands in 1975. Approximately 80% of these

Results

Those who were lost to follow-up were younger, had a higher BMI and greater waist circumference, a higher mean FPG, and more often had baseline IFG than those with follow-up data available after 10 years (Supplementary Table S2). The patterns of loss to follow-up were similar across the ethnic groups. The proportions of people with a family history of type 2 diabetes were similar for those with and without follow-up data.

Table 1 presents the baseline characteristics of the study population

Discussion

We found a higher 10-year cumulative incidence of type 2 diabetes among South-Asian Surinamese and African Surinamese than among ethnic Dutch. This ethnic difference was even more striking for those with IFG than for those with normoglycemia at baseline. In line with this finding, we observed that the associations of both baseline IFG and FPG with incident type 2 diabetes were stronger among the South-Asian Surinamese and, to a lesser extent, African Surinamese than among the ethnic Dutch. This

Conflict of interest

The authors declare that they have no conflict of interest.

Acknowledgements

We are most grateful to the participants of the SUNSET and HELIUS study and the management team, research nurses, interviewers, research assistants and other staff who have taken part in gathering the data of this study.

The SUNSET study was funded by The Netherlands Organisation for Health Research and Development (ZonMw) and the Academic Medical Centre (AMC). The HELIUS study is conducted by the Academic Medical Center Amsterdam and the Public Health Service of Amsterdam. Both organisations

References (20)

There are more references available in the full text version of this article.

Cited by (0)

View full text