Recent genome-wide association studies have identified multiple loci associated with BMI or the waist:hip ratio (WHR). However, evidence on gene–lifestyle interactions is still scarce, and investigation of the effects of well-documented dietary and other lifestyle data is warranted to assess whether genetic risk can be modified by lifestyle. We assessed whether previously established BMI and WHR genetic variants associate with obesity and weight change in the Finnish Diabetes Prevention Study, and whether the associations are modified by dietary factors or physical activity. Individuals (n 459) completed a 3 d food record and were genotyped for twenty-six BMI- and fourteen WHR-related variants. The effects of the variants individually and in combination were investigated in relation to obesity and to 1- and 3-year weight change by calculating genetic risk scores (GRS). The GRS were separately calculated for BMI and the WHR by summing the increasing alleles weighted by their published effect sizes. At baseline, the GRS were not associated with total intakes of energy, macronutrients or fibre. The mean 1- and 3-year weight changes were not affected by the BMI or WHR GRS. During the 3-year follow-up, a trend for higher BMI by the GRS was detected especially in those who reported a diet low in fibre (P for interaction = 0·065). Based on the present findings, it appears unlikely that obesity-predisposing variants substantially modify the effect of lifestyle modification on the success of weight reduction in the long term. In addition, these findings suggest that the association between the BMI-related genetic variants and obesity could be modulated by the diet.

A cluster of variants in the fat mass and obesity-associated (FTO) gene are associated with the common form of obesity. Well-documented dietary data are required for identifying how the genetic risk can be modified by dietary factors. The objective of the present study was to investigate the associations between the FTO risk allele (rs9939609) and dietary intake, and to evaluate how dietary intake affects the association between FTO and BMI in the Finnish Diabetes Prevention Study during a mean follow-up of 3·2 years. A total of 479 (BMI >25 kg/m2) men and women were genotyped for rs9939609. The participants completed a 3 d food record at baseline and before every annual study visit. The average intakes at baseline and during the years 1, 2 and 3 were calculated. At baseline, the FTO variant rs9939609 was not associated with the mean values of total energy intake, macronutrients or fibre. At baseline, a higher BMI by the FTO risk genotype was detected especially in those who reported a diet high in fat with mean BMI of 30·6 (sd 4·1), 31·3 (sd 4·6) and 34·5 (sd 6·2) kg/m2 for TT, TA and AA carriers, respectively (P =0·005). Higher BMI was also observed in those who had a diet low in carbohydrates (P =0·028) and fibre (P =0·015). However, in the analyses adjusted for total energy intake, age and sex, significant interactions between FTO and dietary intakes were not found. These findings suggest that the association between the FTO genotype and obesity is influenced by the components of dietary intake, and the current dietary recommendations are particularly beneficial for those who are genetically susceptible for obesity.

Objectives: The Finnish Diabetes Prevention Study (DPS) was a randomized intervention program that evaluated the effect of intensive lifestyle modification on the development of diabetes mellitus type 2 in patients with impaired glucose tolerance. As such, a program is demanding in terms of resources; it is necessary to assess whether it would be money well spent. This determination was the purpose of this study.

Methods: We developed a simulation model to assess the economic consequences of an intervention like the one studied in DPS in a Swedish setting. The model used data from the trial itself to assess the effect of intervention on the risk of diabetes and on risk factors for cardiovascular disease. Results from the United Kingdom Prospective Diabetes Study were used to estimate the risk of cardiovascular disease and stroke. Cost data were derived from Swedish studies. The intervention was assumed to be applied to eligible patients from a population-based screening program of 60-year-olds in the County of Stockholm from which the baseline characteristics of the patients was used.

Results: The model predicted that implementing the program would be cost-saving from the healthcare payers' perspective. Furthermore, it was associated with an increase in estimated survival of .18 years. Taking into consideration the increased consumption by patients due to their longer survival, the predicted cost-effectiveness ratio was 2,363€ per quality-adjusted life-year gained.

Conclusions: Lifestyle intervention directed toward high-risk subjects would be cost-saving for the healthcare payer and highly cost-effective for society as a whole.

The aim of the Finnish Diabetes Prevention Study is to assess the efficacy of an intensive diet–exercise programme in preventing or delaying type 2 diabetes in individuals with impaired glucose tolerance (IGT) and to evaluate the effect of the programme on the risk factors of atherosclerotic vascular diseases and the incidence of cardiovascular events. In this ongoing study, a total of 523 overweight subjects with IGT based on two oral glucose tolerance tests were randomized to either an intervention group or a control group. The main measure in the intervention group is individual dietary advice aimed at reducing weight and intake of saturated fat and increasing intake of dietary fibre. The intervention subjects are individually guided to increase their level of physical activity. The control group receives general information about the benefits of weight reduction, physical activity and healthy diet in the prevention of diabetes. A pilot study began in 1993, and recruitment ended in 1998. By the end of April 1999 there were 65 new cases of diabetes, 34 drop-outs and one death. The weight reduction was greater (-4.6 kg) at 1 year in the intervention group (n = 152) than in the control group (n = 143, -0.9 kg, P < 0.0001), and this difference was sustained in the second year of follow-up. At 1 year 43.4 % and at 2 years 41.8 % of the intervention subjects had achieved a weight reduction of at least 5 kg, while the corresponding figures for the control subjects were 14.0 and 12.0 % (P < 0.001 between the groups). At 1 year the intervention group showed significantly greater reductions in 2 h glucose, fasting and 2 h insulin, systolic and diastolic blood pressure, and serum triglycerides. Most of the beneficial changes in cardiovascular risk factors were sustained for 2 years. These interim results of the ongoing Finnish Diabetes Prevention Study demonstrate the efficacy and feasibility of the lifestyle intervention programme.

Altogether twenty-six elderly subjects (aged 65–74 years) with persistent impaired glucose tolerance (World Health Organization (1985) criteria) identified in a population-based study, were randomly treated either with chromium-rich yeast (160 μg Cr/d) or with placebo for 6 months. The 24 h urinary Cr increased from 0.13 (se 0.03) to 0.40 (se 0.06) μg/d in the Cr group (n 13) but no change was found in the placebo group (n 11) (0.13 (se 0.02) v. 0.11 (se 0.02) μg/d). No significant change was observed in the oral glucose tolerance test (glucose dose 75 g; 0, 1 and 2 h blood glucose respectively): 5.3 (se 0.1), 9.3 (se 0.3), 8.2 (se 0.3) mmol/l v. 5.0 (se 0.1), 8.5 (se 0.4), 7.3 (se 0.5) mmol/l in the Cr group; 4.9 (se 0.2), 9.2 (se 0.6), 8.1 (se 0.3) mmol/l v. 4.8 (se 0.2), 8.5 (se 0.5), 7.0 (se 0.6) mmol/l in the placebo group (baseline v. 6 months). Glycosylated haemoglobin, plasma insulin, C-peptide and apolipoprotein Al and B levels remained unchanged, and no improvement was seen in serum total cholesterol (6.2 (se 0.3) v. 6.4 (se 0.3) mmol/l for the Cr group, 6.2 (se 0.4) v. 6.5 (se 0.3) mmol/l for the placebo group), high-density-lipoprotein-cholesterol (1.1 (se 0.1) v. 1.2 (se 0.1) mmol/l for the Cr group, 1.0 (se 0.1) v. 1.1 (se 0.1) mmol/l for the placebo group) or triacylglycerols (2.5 (se 0.4) v. 2.0 (se 0.4) mmol/l for the Cr group, 2.4 (se 0.2) v. 2.5 (se 0.2) mmol/l for the placebo group). The present results indicate that Cr supplementation does not improve glucose tolerance or serum lipid levels in elderly subjects with stable impaired glucose tolerance.