New research from the UK shows that, in patients with recently diagnosed type 2 diabetes, 6.5 hours of additional dietary advice sessions lead to improvement in blood sugar control compared with patients who receive usual care. However, increased activity conferred no additional benefit when combined with the diet intervention. The Article, published Online First by The Lancet, is by Dr Robert Andrews, University of Bristol, UK.
The study assessed 593 adults aged 30—80 years in whom type 2 diabetes had been diagnosed 5—8 months earlier. Of these, 99 were assigned to usual care, 248 to diet advice only, and 246 to diet advice plus exercise. Usual care patients received an initial dietary consultation plus follow-up every 6 months. Diet-only group patients were given a dietary consultation every 3 months with additional nurse support each month. Diet and exercise patients received the same as diet only patients but were also asked to do 30 minutes of brisk walking five times a week (with activity assessed by pedometers that showed good adherence).
The researchers found that in the usual care group, blood sugar control had worsened, with mean HbA1c (a method of assessing blood sugar control) increasing from 6.72% to 6.86% over 6 months, before falling back to 6.81% at 12 months. In the diet advice group, HbA1c fell from a mean 6.64% pre-intervention to 6.57% at 6 months and 6.55% at 12 months. Exercise did not confer additional benefit on top of the diet advice, apart from in those patients with the highest HbA1c, insulin resistance, or body-mass index at baseline.
The authors say: "These findings suggest that intervention at this early stage should focus on improving diet, since the additional cost of training health-care workers to promote activity might not be justified."
They add there could be a number of reasons for the apparent lack of effect of increased activity: that it was not intense enough, or that it was too early in the disease process for exercise to show an effect. It is also possible, say the authors, that individuals in the diet and exercise group modified their behavior and diluted the effect of both interventions, for example, rewarding themselves with extra food due to increased exercise.
They conclude: "Further research is needed to clarify whether more intensive or different types of activity, or activity advice offered at a later stage of diabetes will add benefits to diet interventions, or whether benefits of activity interventions will become more apparent after 1 year."
In a linked Comment, Dr Frank B Hu, Harvard School of Public Health, Boston, MA, USA, says that the changes in HbA1c, while small, are clinically meaningful, since a decrease of 1% in HbA1c can reduce rates of major cardiovascular disease by 12—16% and microvascular complications by 37%.
He concludes: "Translation of these results into community settings requires concerted efforts by patients, dietitians, and clinicians… There is little doubt that improved nutrition and physical activity are beneficial for individuals with or without diabetes, and research into the most effective way to deliver these benefits (including individual behavioural changes and creation of a supportive food and social environment) deserves high priority."
To arrange an interview with Dr Robert Andrews, University of Bristol, UK, and other authors, please contact Joanne Fryer, Press Office. T) +44 (0)117 331 7276 / +44 (0) 7747 768805 E) Joanne.Fryer@bristol.ac.uk / rob.andrews@bristol.ac.uk
For Dr Frank B Hu, Harvard School of Public Health, Boston, MA, USA, please contact Todd Datz in Communications. T) +1 617-432-8413 E) tdatz@hsph.harvard.edu
Journal
The Lancet