A meal replacement regimen improves blood glucose levels in prediabetic healthy individuals with impaired fasting glucose

Abstract

Objective

The aim of this study was to investigate the effect of a 6-wk intervention with either lifestyle intervention (increased physical activity and a low-calorie diet) or a meal replacement regimen on glycemic control in patients who are prediabetic and have impaired fasting glucose.

Methods

Forty-two overweight or obese men and women (age 54 ± 8 y; weight 95.1 ± 11.9 kg; body mass index [BMI] 32.8 ± 2.89 kg/m²) were included in this randomized controlled clinical trial. Patients in the lifestyle group (LS; n = 14) received dietary counseling sessions (fat-restricted low-calorie diet) and instructions on how to increase physical activity. Patients in the meal replacement group (MR; n = 28) were instructed to replace two daily meals with a low-calorie, high soy-protein drink with a low glycemic index.

Results

Both interventions resulted in a significant decrease in body weight and BMI, although the reduction was more pronounced (P < 0.05) in the MR group. In both groups, glucose concentrations decreased significantly (LS: −12 mg/dL, P < 0.01; MR: −11 mg/dL, P < 0.01), and mean glucose levels returned to the normal range. Insulin (LS: −1 μU/mg [not significant]; MR: −6.3 μU/mg, P < 0.01) and homeostasis model assessment of insulin resistance (HOMA-IR; LS −0.92, P < 0.01; MR: −2.1, P < 0.01) were also significantly lower following both interventions; again improvements were more pronounced in the MR group (insulin: P < 0.05; HOMA P < 0.01)

Conclusion

It can be concluded that meal replacement is an effective intervention for rapid improvement of elevated fasting glucose and increased insulin concentrations, these being important biomarkers of the prediabetic state. The 6-wk intervention has shown that the effect of meal replacement on fasting blood glucose was comparable to the effect of lifestyle intervention. The alterations in BMI, insulin, and HOMA-IR were significantly more pronounced following the meal replacement regimen.

Introduction

Formal guidelines suggest that individuals showing increased fasting glucose concentrations (>100 mg/dL) that do not meet the criteria for diabetes mellitus (>126 mg/dL) should be diagnosed with prediabetes [1]. Additionally, the presence of impaired glucose tolerance (IGT; 2-h values in the oral glucose tolerance test of 140–199 mg/dL and an HbA_1c range of 5.7%–6.4%) also identifies individuals with prediabetes. In these individuals, the postprandial phase is characterized by a large and more prolonged increase in blood glucose concentrations. It is estimated that approximately 10% of the adult population in Western societies have prediabetes [2]. Although individuals with prediabetes are healthy and per definition not diabetic, there is good scientific evidence to suggest they have an increased risk for the conversion to type 2 diabetes mellitus (T2DM) [3].

It has been demonstrated that the reconversion from the prediabetic state to normoglycemia may substantially reduce the risk for the development of T2DM and its associated complications [4]. Furthermore, it has been shown that the prediabetic state also is associated with early forms of neuropathy, nephropathy, or retinopathy [5]. Therefore, there is general agreement that individuals with prediabetes should be treated by therapeutic lifestyle interventions (TLC) or, in the case of malcompliance with TLC, by pharmacotherapy [6].

The Diabetes Prevention Program and other clinical trials have shown that prediabetic conditions and insulin resistance (IR) can be improved [7]. Increasing evidence suggests that the risk for T2DM can be substantially reduced if one is physically active, loses weight, and makes wise food choices [8]. It has been demonstrated that meal replacement regimens are associated with fast weight loss and improvements in metabolic risk factors [9], [10], [11]. A recent Medline search showed that the effect of meal replacement on glycemic control and measures of IR has not been fully investigated in individuals with prediabetes. Therefore, in this study, the influence of a very-low-calorie meal replacement regimen by a soy-protein drink on changes in fasting glucose and insulin levels and the homeostasis model assessment of insulin resistance (HOMA-IR) were investigated. The effects of the meal replacement regimen were compared with those of a lifestyle intervention with a fat-restricted, low-calorie diet in combination with increased physical activity.