Elsevier

The Lancet

Volume 368, Issue 9548, 11–17 November 2006, Pages 1673-1679
The Lancet

Articles
Sustained reduction in the incidence of type 2 diabetes by lifestyle intervention: follow-up of the Finnish Diabetes Prevention Study

https://doi.org/10.1016/S0140-6736(06)69701-8Get rights and content

Summary

Background

Lifestyle interventions can prevent the deterioration of impaired glucose tolerance to manifest type 2 diabetes, at least as long as the intervention continues. In the extended follow-up of the Finnish Diabetes Prevention Study, we assessed the extent to which the originally-achieved lifestyle changes and risk reduction remain after discontinuation of active counselling.

Methods

Overweight, middle-aged men (n=172) and women (n=350) with impaired glucose tolerance were randomly assigned to intensive lifestyle intervention or control group. After a median of 4 years of active intervention period, participants who were still free of diabetes were further followed up for a median of 3 years, with median total follow-up of 7 years. Diabetes incidence, bodyweight, physical activity, and dietary intakes of fat, saturated fat, and fibre were measured.

Findings

During the total follow-up, the incidence of type 2 diabetes was 4·3 and 7·4 per 100 person-years in the intervention and control group, respectively (log-rank test p=0·0001), indicating 43% reduction in relative risk. The risk reduction was related to the success in achieving the intervention goals of weight loss, reduced intake of total and saturated fat and increased intake of dietary fibre, and increased physical activity. Beneficial lifestyle changes achieved by participants in the intervention group were maintained after the discontinuation of the intervention, and the corresponding incidence rates during the post-intervention follow-up were 4·6 and 7·2 (p=0·0401), indicating 36% reduction in relative risk.

Interpretation

Lifestyle intervention in people at high risk for type 2 diabetes resulted in sustained lifestyle changes and a reduction in diabetes incidence, which remained after the individual lifestyle counselling was stopped.

Introduction

The pandemic of type 2 diabetes is an enormous public health problem.1, 2 Studies using lifestyle intervention in people with impaired glucose tolerance have shown that the progress to manifest type 2 diabetes can be prevented or postponed.3, 4, 5, 6, 7, 8 Lifestyle intervention in these studies lasting for 3–6 years emphasised bodyweight control, physical activity, and dietary modification. Reduction in relative risk achieved in the intervention group compared with the control group ranged from 30% to 67%, as shown in a recent meta-analysis.9 The Finnish Diabetes Prevention Study5 and the US Diabetes Prevention Program6 both revealed a 58% relative risk reduction in the progression from impaired glucose tolerance to type 2 diabetes, during a mean intervention period of about 3 years.

However, whether the risk reduction achieved during active counselling for lifestyle changes will last after discontinuation of the intervention is not known. The extended follow-up of the Diabetes Prevention Study was designed to assess the long-term results of the lifestyle intervention originally aimed at reducing the risk for developing type 2 diabetes in high-risk individuals.

Section snippets

Methods

The Diabetes Prevention Study was a randomised controlled trial aimed at prevention of type 2 diabetes by lifestyle intervention. The study design has been described in detail previously.10 The study protocol was approved by the ethics committee of the National Public Health Institute in Helsinki, Finland, and all study participants gave written informed consent. Randomisation started in 1993 and was completed in 1998 (figure 1). The first interim analysis was done in March, 2000.5 According to

Results

The total number of cases of diabetes diagnosed during the overall follow-up of 7 years was 75 in the intervention group and 110 in the control group (figure 1). The incidence rates were 4·3 (95% CI 3·4–5·4) and 7·4 (6·1–8·9) per 100 person-years in the intervention and control group, respectively (p=0·0001 log-rank test). The corresponding hazard ratio was 0·57 (0·43–0·76; figure 2). The cumulative incidence of diabetes at year 6 was 23% in the intervention group and 38% in the control group,

Discussion

Individually randomised controlled lifestyle intervention studies have shown the benefit of healthy lifestyle on delaying the deterioration of glucose tolerance to manifest type 2 diabetes, at least as long as the inter–vention continues.5, 6, 7, 8 Our study with a median of 7 years total follow-up shows that a marked difference in the cumulative incidence of diabetes can be sustained after the discontinuation of active counselling. The absolute difference in diabetes risk between the

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