Helsinki, Finland - The effects of lifestyle intervention on diabetes risk do not disappear after active counseling has stopped, a new follow-up of the Finnish Diabetes Prevention Study shows [1].

Three years after the end of the study, those in the intervention group still had a reduced incidence of type 2 diabetes compared with the control group, Dr Jaana Lindstrom (National Public Health Institute, Helsinki, Finland) and colleagues report in the Lancet.

In an accompanying comment [2], Dr Ronald B Goldberg (Diabetes Research Institute, University of Miami, FL) says that the latest results from Finland show that the initial intervention in the lifestyle group "had a sustained effect that appeared to last almost as long again as the period of active counseling."

He cautions, however, that the findings need to be confirmed in other ethnic groups, such as those being followed in the ongoing US Diabetes Prevention Program Outcome Study, for which he is an investigator.

The Finnish Diabetes Prevention Study assessed the effects of active counseling with regard to lifestyle changes in overweight middle-aged men and women, who were randomly assigned to the counseling arm (n=265) or the control group (n=257) for four years.

At the end of this period, the incidence of new diabetes was cut by 58% in the intervention group. These results were reported in 2000 and published a year later in the New England Journal of Medicine. Two years later, the final results of the US Diabetes Prevention Program (DPP) showed an identical reduction in new type 2 diabetes with a similar intensive lifestyle intervention.

Now the Finnish investigators have further followed up those who were still free of diabetes at the end of their study, for a median of three more years, monitoring diabetes incidence, body weight, physical activity, and dietary intake of fat, saturated fat, and fiber.

At the end of this three years, the incidence of type 2 diabetes was 4.6 per 100 person-years in the group that had undergone the counseling, compared with 7.2 per 100 person-years in the control group (p=0.0401), indicating a 36% reduction in relative risk in the intervention group.

The risk reduction was related to the success in achieving the intervention goals of weight loss, reduced intake of total and saturated fat, increased intake of dietary fiber, and increased physical activity.

"From a public-health point of view there is an important message: an intensive lifestyle intervention lasting for a limited time can yield long-term benefits in reducing the risk of type 2 diabetes in high-risk individuals," say Lindstrom et al.

Goldberg says that although the benefit seen in the follow-up period is smaller than in the original study, it is still significant. "Overall, the relative reduction in diabetes incidence over the entire seven-year follow-up in the lifestyle group was 43%, similar to the 46% reduction noted in the diet-plus-exercise intervention group of the six-year [Chinese] Da Qing study, reported in 1997," he notes.

However, Lindstrom commented to heartwire that the results "do not allow us to distinguish between the carryover effect from the intervention and the ongoing effect of lifestyle during the postintervention period.

"Perhaps it was a bit of both," she added, "but definitely they [the intervention group] had a better lifestyle, so it must have had some effect."

The intervention as used in the original study has formed the basis for the implementation of a program for the prevention of type 2 diabetes in five hospital districts in Finland, covering about 1.5 million of Finland's population of 5 million, she added.