A 2012 systematic review of 21 RCTs examined the effect of group-based diabetes education on HbA1c in 2833 adults with T2DM.1 Intervention groups participated in at least 1 group session lasting an hour led by a health professional or team (eg, physician, nurse, diabetes educator); controls received usual care. Most trials involved 6 to 20 hours of group-based education delivered over 1 to 10 months, although some trials continued the intervention for as long as 24 months. The mean HbA1c at baseline across all patients was 8.23%.
Professional-led group visitsimprove HbA1c
Group education resulted in a significant reduction in HbA1c compared with controls at 6 months (13 trials; 1883 patients; mean difference [MD]=−0.44%; 95% confidence interval [CI], −0.69 to −0.19), 12 months (11 studies; 1503 patients; MD=−0.46%; 95% CI, −0.74 to −0.18), and 24 months (3 studies; 397 patients; MD=−0.87%; 95% CI, −1.25 to −0.49). The trials had high heterogeneity, except for the 3 trials with a 24-month end-point (I2 = 0). Most studies had a moderate or high risk of bias.
A larger 2017 meta-analysis enrolling 8533 adults with T2DM came to similar conclusions, although it included a small number of nonrandomized trials (40 RCTs, 3 cluster RCTs, and 4 controlled clinical trials).2 Thirteen of the RCTs overlapped with the previously described systematic review.1 Interventions had to include at least 1 group session with 4 or more adult patients lasting at least 1 hour. In most studies, interventions continued between 4 and 12 months, although some ran 60 months. Controls received usual care. The mean HbA1c at baseline across all patients was 8.3%.
Group-based education compared with controls reduced HbA1c at 6 to 10 months (30 trials, N not given; MD=−0.3%; 95% CI, −0.48 to −0.15), 12 to 14 months (27 trials, N not given; MD=−0.3%; 95% CI, −0.49 to −0.17), and 36 to 48 months (5 trials, N not given; MD=−0.9%; 95% CI, −1.52 to −0.34). In a subgroup analysis, peer-led group visits had no effect (5 trials, 1066 patients; MD=−0.02%; 95% CI, −0.12 to 0.16).
Patients on oral agents alone showed a larger benefit than patients using insulin (38 trials, 5871 patients; −0.81 vs −0.19; P < .0001). Authors of the meta-analysis classified most studies as having a moderate to high risk of bias, with only 4 having low risk.
Duration of intervention: Longer is better for HbA1c values
Another systematic review analyzed 13 RCTs with 4652 patients 16 years and older with T2DM or type 1 diabetes to assess the effect of group visits on HbA1c.3 The review excluded studies that didn’t include a health care provider who could prescribe, diagnose, assess, and refer patients when appropriate.
Most interventions ran 3 to 12 months, although one lasted 36 months. (Two RCTs overlapped with the 2012 review, and 2 others with the 2017 review.) Group medical visits resulted in a significant decrease in HbA1c at the end of the intervention period (MD=−0.46%; 95% CI, −0.80 to −0.13) compared with controls. A meta-regression analysis suggested that ongoing treatment (for as long as 3 years) decreased HbA1c more than a shorter treatment duration (by 0.25% per year of treatment), whereas the frequency of treatments didn’t alter the effect. Overall, the trials were heterogenous and most had a high risk of bias.
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