Background
Type 2 diabetes is a significant public health concern. With the completion of the Diabetes Prevention Program, there has been a proliferation of studies attempting to translate this evidence base into practice. However, the cost, effectiveness, and cost-effectiveness of these adapted interventions is unknown.
Objective
The purpose of this systematic review was to conduct a comprehensive meta-analysis to synthesize the effectiveness, cost, and cost-effectiveness of lifestyle diabetes prevention interventions and compare effects by intervention delivery agent (dietitian vs non-dietitian) and channel (in-person vs technology-delivered).
Methods
English and full-text research articles published up to July 2015 were identified using the Cochrane Library, PubMed, ERIC, CAB Direct, Science Direct and Google Scholar. Sixty-nine studies met inclusion criteria. Most employed both dietary and physical activity intervention components (four of 69 were diet-only interventions). Changes in weight, fasting and 2-hour blood glucose concentration, and hemoglobin A1c were extracted from each article. Heterogeneity was measured by the I^2 index, and study-specific effect sizes or mean differences were pooled using a random effects model when heterogeneity was confirmed.
Results
Participants receiving intervention with nutrition education experienced a reduction of 2.07 kg (95% CI: 1.52 to 2.62; p<0.001; I2=90.99%, 95% CI: 88.61% to 92.87%) in weight at 12 months with effect sizes over time ranging from small (0.17, 95% CI: 0.04 to 0.30; p=0.012; I2= 86.83%, 95% CI: 80.42% to 91.14%) to medium (0.65, 95% CI: 0.49 to 0.82; p<0.001; I2= 98.75%, 95% CI: 98.52% to 98.94). Effect sizes for 2-h blood glucose and HbA1c changes ranged from small to medium. The meta-regression analysis revealed a larger relative weight loss in dietitian-delivered interventions than in those delivered by non-dietitians (full sample: −1.0 kg; US subsample: −2.4 kg), and did not find statistical evidence that the delivery channel was an important predictor of weight loss. The average cost per kg weight loss ranged from $53.87 over 2 months to $1,005.36 over 12 months. The cost of intervention per participant delivered by dietitians was lower than interventions delivered by non-dietitians, though few studies reported costs.
Conclusions
Lifestyle interventions are effective in reducing body weight and glucose-related outcomes. Dietitian-delivered interventions, compared to those delivered by other personnel, achieved greater weight reduction. No consistent trend was identified across different delivery channels.