Study on lifestyle-intervention and impaired glucose tolerance Maastricht (SLIM): design and screening results

Abstract

The study on lifestyle-intervention and impaired glucose tolerance Maastricht (SLIM) is a 3 years randomised clinical trial designed to evaluate the effect of a combined diet and physical activity intervention program on glucose tolerance in a Dutch population at increased risk for developing type 2 diabetes. Here the design of the lifestyle-intervention study is described and results are presented from the preliminary population screening, conducted between March 1999 and June 2000. In total, 2820 subjects with an increased risk of having disturbances in glucose homeostasis (i.e. age >40 years and BMI>25 kg/m² or a family history of diabetes) underwent a first oral glucose tolerance test (OGTT). Abnormal glucose homeostasis was detected in 826 subjects (30.4%): 226 type 2 diabetes (type 2DM, 8.3%), 215 impaired fasting glucose (IFG, 7.9%) and 385 impaired glucose tolerance (IGT, 14.2%). Both increasing age and BMI were strongly related to the prevalence of IGT and diabetes. After a second OGTT, 114 subjects with glucose intolerance and in otherwise good health were eligible for participation in the intervention study (SLIM). The high prevalence of disturbances in glucose homeostasis observed in the preliminary screening underscore the importance of early (lifestyle) interventions in those at risk for developing diabetes. SLIM will address this topic in the Dutch population.

Introduction

Type 2 diabetes mellitus is rapidly becoming one of the main health issues in the 21st century. Prevalence has increased explosively in the last two decades, and global estimates indicate a further rise from a current 150 million people with diabetes, to 300 million in 2025 [1], [2]. Impaired glucose tolerance (IGT) is the obligatory transition state preceding type 2 diabetes. Prevalence of IGT varies widely between populations, from as low as 2.0% in rural populations to more than 20% in high-risk populations [3]. The cumulative incidence of type 2 diabetes in subjects with IGT ranged from 3.6 to 8.7% per year in six prospective studies [4], and is strongly related to the fasting and the 2-h plasma glucose concentrations at the time of IGT recognition [4], [5]. The most important modifiable risk factor for progression from IGT to diabetes is obesity. Body mass index (BMI) at the time of IGT recognition is a strong predictor of progression, independently of fasting and 2-h blood glucose concentrations [4]. Dietary factors, especially a high fat intake, are also related to the risk of conversion from IGT to diabetes [6].

Several recent studies have reported the feasibility and efficacy of interventions to prevent or delay the progression to type 2 diabetes in subjects with IGT [7], [8], [9], [10], [11], [12], [13]. Acarbose, [13], as well as metformin [12], have been shown to reduce the incidence of diabetes in a population with IGT. Other studies have focused on the potential of lifestyle changes to reduce the progression rate from IGT to type 2 diabetes. The Finnish diabetes prevention study (DPS) [11] and the US diabetes prevention program (DPP) [12] reported that weight-loss, changes in dietary intake, and increased physical activity resulted in a 58% reduction in the incidence of diabetes after a mean follow-up of only 3 years. Moreover, lifestyle-intervention was much more effective in reducing the incidence of diabetes than pharmacological intervention (i.e. metformin) [12]. It is important to confirm these observations in different populations, with a different dietary and physical activity background, and a different attitude towards changing lifestyle-habits.

The study on lifestyle-intervention and impaired glucose tolerance Maastricht (SLIM) is a 3 years randomised clinical trial designed to evaluate the effect of a combined diet and physical activity intervention program on glucose tolerance in a Dutch population at increased risk for developing type 2 diabetes. Furthermore, we will consider changes in anthropometric measurements, aerobic capacity and cardiovascular risk factors. Additional measurements will be performed in subgroups of the study population in a search for underlying mechanisms.

The objective of this report is to describe the design of the lifestyle-intervention study and to evaluate the results of the preliminary population screening, from which the subjects were recruited for the intervention study. Data are presented about the prevalence of disturbances in glucose homeostasis in a middle-aged Dutch population.