Table 1:

Characteristics of 13 randomized controlled trials included in the meta-analysis

StudyStudy durationDuration and frequency of group medical visitsNo. of patientsStudy population% maleOutcomes measuredHbA1c outcomeBP outcome
Clancy et al., 200315176 mo2-h sessions; monthly over 6 moIntervention: 59
Control: 61
Age > 18 yr; type 2 diabetes with HbA1c > 8.5% at most recent evaluation21.7Trust in physician (scale), ADA process-of-care indicators, patient care assessment tool, HbA1c, lipid profilesAt 6 mo: 9.513% in intervention and 9.714% in control; difference not significantNot measured
Clancy et al., 200718,19 and 20082012 mo2-h sessions; monthly over 12 moIntervention: 96
Control: 90
Age > 18 yr; poorly controlled type 2 diabetes (HbA1c > 8%)28Emergency department visits, inpatient stays, primary and specialty outpatient visits, total charges, HBA1c testing, lipid profiles, adherence to ADA guidelines, cancer screensNot measured; instead study looked at no. of patients who received HbA1c testingNot measured
Cohen et al., 2011216 mo2-h sessions over 6 mo; weekly for 4 wk, then monthly for 5 moIntervention: 50
Control: 49
Veterans with type 2 diabetes; HbA1c > 7.0%, LDL cholesterol > 100 mg/dL (or > 70 mg/dL if coronary artery disease present); BP > 130/80 mm HgIntervention: 100
Control: 96
HbA1c, LDL cholesterol, BP, goal attainment of these values, diabetes self-care behaviour, prescribing (medications) between groups, no. of visits with primary care providerTarget goals reached by 40.5% in intervention v. 20.4% in control (p = 0.03); patients in intervention group had higher odds of attaining HbA1c goalsTarget systolic BP (< 130 mm Hg) reached by 50% in intervention and 32.7% in control (p = 0.015); patients in intervention group had higher odds of attaining systolic BP goals
Edelman et al., 20102212.8 mo90–120 min per session; every 2 mo over 12 mo; total 7 sessionsIntervention: 133
Control: 106
Veterans with poorly controlled diabetes (HbA1c ≥ 7.5%) and hypertension (systolic BP > 140 mm Hg, diastolic BP > 90 mm Hg); type of diabetes not specifiedIntervention: 95.5
Control: 96.2
Systolic and diastolic BP, HbA1c, self-reported medication adherenceMean decrease 0.8% in intervention and 0.5% in control; difference not significant (p = 0.159)Mean decrease in systolic BP was 13.7 mm Hg in intervention v. 6.4 mm Hg in control (p = 0.011)
Naik et al., 20112312 mo60-min sessions; 4 sessions; every 3 wk over 3 moIntervention: 45
Control: 42
Veterans aged 50–90 yr with a primary care provider; type 2 diabetes; mean HbA1c 7.5% 6 mo before studyUnknownHbA1c, diabetes self-efficacy scale, diabetes specific knowledge and understanding scaleAt 1 yr: 8.05% ± 1.40% in intervention v. 8.64% ± 1.39% in control (p = 0.05)Not measured
Rygg et al., 20122412 mo5-h sessions; every 2 wk over 6 wk, or every 3 wk over 9 wk, depending on siteIntervention: 73
Control: 73
Age > 18 yr; type 2 diabetes; consultation with general practitioner in past 3 yr“Approximately 50%”HbA1c, patient activation, diabetes knowledge, BP, weight, BMI, total and HDL cholesterol, triglycerides, creatinine, oral glucose-lowering medication, visits with health care personnel in past 3 mo, satisfaction with diabetes treatment, problem areas in diabetes, EQ-VAS, SF-36 (physical and mental health domains), self- management (diet, foot care and blood glucose)At 12 mo: no significant difference (p = 0.432), except in subgroup analysis of patients with highest HbA1c (> 7.7%) at baseline (8.2% ± 1.4% in intervention group v. 8.8% ± 1.4% in control group; p = 0.012)Systolic BP intervention: 140.6 (17.1), control: 143.7 (20.8). diastolic BP intervention: 82.6 (10.3), control 83.3 (10.3)
Sadur et al., 19992512 mo2-h sessions; monthly over 6 moIntervention: 82
Control: 74
Age 16–75 yr; type 1 and 2 diabetes; HbA1c > 8.5%, or no HbA1c test performed in previous yrIntervention: 58.8
Control: 55.7
HbA1c, self-reported changes in self-care practices, self-efficacy, satisfaction, utilization of inpatient and outpatient health care≥ 5 mo after randomization: 8.18% in intervention and 9.33% in control (p < 0.0001)Not measured
Schillinger et al., 20092612 mo90-min sessions; monthly over 9 moIntervention: 104 Control (usual care): 108 3rd arm (wkly automated telephone support with nurse follow- up): 112Adult patients with type 2 diabetes; uninsured with high school education or less; ≥ 1 primary care visit in past yr; recent HbA1c ≥ 8.0%Intervention: 36.3
Control: 44.7
1-yr changes in structure (patient assessment of chronic Illness care), communication processes (interpersonal processes of care) and outcomes (behavioural, functional and metabolic)No difference between groups (9.0% ± 2.0% in both groups; p = 0.3)Systolic BP 138.9 ± 20.3 mm Hg in intervention and 141.5 ± 23.9 mm Hg in usual-care group (p = 0.1); diastolic BP 75.5 ± 11.3 mm Hg in intervention and 78.5 ± 18.5 mm Hg in usual-care group (p = 0.08)
Taveira et al., 2010274 mo2-h sessions; weekly over 4 wkIntervention: 58
Control: 51
Veterans aged ≥ 18 yr with type 2 diabetes; HbA1c 7%–9% in previous 6 moIntervention: 91.4
Control: 100
HbA1c, BP (systolic < 130 mm Hg, diastolic < 80 mm Hg), lipids, tobacco useTarget reached by 40.4% in intervention and 21.6% in control; absolute mean change −0.9 ± 1.6 in intervention and 0.0 ± −1.5 in controlTarget systolic BP reached by 65.5% in intervention and 39.9% in control; absolute mean change −7.3 ± 20.3 mm Hg in intervention and −1.7 ± −19.6 mm Hg in control. Target diastolic BP reached by 65.5% in intervention and 68.6% in control; absolute mean change −6.5 ± 10.0 mm Hg in intervention and 1.0 ± 10.8 mm Hg in control
Taveira et al., 2011286 mo90-min sessions; weekly for 4 wk, then monthly for 5 moIntervention: 44
Control: 44
Veterans with depression and type 1 or 2 diabetes; HbA1c > 6.5% in previous 6 moIntervention: 100
Control: 95.5
HbA1c < 7% at 6 mo, adherence to ADA guidelines (systolic BP < 130 mm Hg, diastolic BP < 80 mm Hg), total, LDL and HDL cholesterol, tobacco cessation, change in 10-yr coronary event risk at 6 mo, depression symptoms7.4% ± 1.2% in intervention v. 8.4% ± 2.0% in control group (p < 0.05)Systolic BP 123.4 ± 12.3 mm Hg in intervention and 127.0 ± 17.3 mm Hg in control (p < 0.05 from baseline)
Trento et al., 2002,29 200130 and 2004314 yrDuration of session not stated; session every 3 moIntervention: 56
Control: 56 (42 in each group at yr 5)
Type 2 diabetes, treated with diet alone or diet and oral hypoglycemic agents; attended diabetes clinicIntervention: 51.1
Control: 60.7
Weight, fasting blood glucose level, HbA1c, serum creatine, total and HDL cholesterol, triglycerides, microalbumine: creatinine ratio, diabetes-related quality of life, knowledge of diabetes, health behaviours, BP, BMIAt 5 yr after randomization: 7.3% ± 1.0% in intervention and 9.0% ± 1.6% in control (p < 0.001)Not measured
Trento et al., 2005323 yrDuration of session unclear; every 2–3 mo; total 15 sessions over 36 moIntervention: 30
Control: 28
Age < 70 yr; type 1 diabetes with onset before 30 yr; insulin started within 1 yr of diagnosis; ≥ 1 yr previous attendance in clinicIntervention: 61.3
Control: 58.1
Diabetes-related quality of life, knowledge of type 1 diabetes, health behaviours, HbA1c, total and HDL cholesterol, microalbumine:creatinine ratio, complications (hypoglycemic episodes [retrospective]), economic analysisAt 3 yr: 7.88% ± 0.20% in intervention and 8.79% ± 1.38% in control (p = NS)Not measured
Wagner et al., 2001332 yrHalf-day sessions; “periodic” (intervals of 3 mo and 6 mo)Intervention: 278
Control: 429
Age > 30 yr; patients with diabetes (type not specified) using insulin or oral hypoglycemic therapy were “preferentially selected”Intervention: 56
Control: 51.8
Subscales of SF-36 (general health, physical function, emotional role function, social function and pain), bed disability, restricted-activity daysAt 24 mo: no difference between groups (7.9% in both groups; p = 0.9)Not measured
  • Note: ADA = American Diabetes Association, BMI = body mass index, BP = blood pressure, EQ-VAS = EuroQol 5-d measure of health outcome, HDL = high-density lipoprotein, LDL = Low-density lipoprotein, NS = not significant, SF-36 = Medical Outcomes Study 36-item Short Form.