A lifestyle-modification program aimed at changes in diet and increased activity levels seemed to significantly cut the risk of type 2 diabetes that was primarily “overweight” rather than obese and that had elevated fasting glucose levels — but not necessarily impaired glucose tolerance.…
And although the risk of developing diabetes over about three years went down by almost half for those who followed the lifestyle intervention, it dropped even further in the subgroup, a minority, who also had impaired glucose tolerance at baseline.
Since the patients who followed the lifestyle interventions also lost significantly more weight than those who didn’t, “it can be inferred that reduction of total energy intake, increase in physical activity, and subsequent weight reduction observed in the [intervention] group could lead to improvement in glucose tolerance,” write the authors.
Studies supporting the use of interventions to prevent diabetes have usually included patients at higher diabetic risk, as identified by the oral glucose tolerance test (OGTT).
The current study suggests that such interventions may prevent diabetes in patients with impaired fasting glucose, especially those who have been further identified to have other risk markers, such as elevated levels of glycosylated hemoglobin (HbA1c).
In the study, 641 persons 30 to 60 years of age with a body-mass index (BMI) of >24 and a fasting plasma glucose level of 100 to 125 mg/dL from 38 centers were used.
They were randomized to a frequent intervention group (n=311) or to a control group (n=330) for 36 months. The frequent intervention program included nine sessions with the medical staff in which they received individual instructions for lifestyle modification and follow-up support.
The dietary intervention aimed at reducing total energy intake, the group writes, mainly by “controlling fat intake at 20% to 25% of total energy intake and carbohydrate intake at 55% to 60% of total energy intake.” The intervention group was also instructed on how to increase daily activity levels.
Participants in the control group received four similar interventions once yearly during the 36-month study and were also instructed to lose weight.
The frequent intervention group had an estimated cumulative incidence of type 2 diabetes (diagnosed at annual 75-g oral glucose tolerance tests on the basis of World Health Organization criteria) of 12.2%, compared with 16.6% in the control group, for an overall adjusted hazard ratio (HR) of 0.56 (95% CI, 0.36-0.87).
Across the subgroup of participants with impaired glucose tolerance at baseline (n=131 in both randomization groups), the HR for incident diabetes for intervention vs. controls was 0.41 (95% CI, 0.24-0.69), according to a post hoc subgroup analysis.
Among participants with baseline HbA1c levels of at least 5.6%, the corresponding HR was 0.24 (95% CI 0.12-0.48).
The remaining study participants with “isolated” impaired fasting glucose at baseline, or HbA1c levels <5.6%, did not show any significant reduction in incident diabetes risk.
Given the findings, HbA1c level could be an excellent risk marker in screening for lifestyle modification.
Archives of Internal Medicine, August 8, 2011