Effect on cardiovascular disease risk factors of interventions to alter consultations between practitioners and patients with type 2 diabetes: A systematic review and meta-analysis of trials in primary care

$\textbf{Objective:}$ To examine the effect on cardiovascular (CVD) risk factors of interventions to alter consultations between practitioners and patients with type 2 diabetes. $\textbf{Search Strategy:}$ Electronic and manual citation searching to identify relevant randomized controlled trials (RCTs). $\textbf{Inclusion Criteria:}$ RCTs that compared usual care to interventions to alter consultations between practitioners and patients. The population was adults aged over 18 years with type 2 diabetes. Trials were set in primary care. $\textbf{Data extraction and synthesis:}$ We recorded if explicit theory-based interventions were used, how consultations were measured to determine whether interventions had an effect on these and calculated weighted mean differences for CVD risk factors including glycated haemoglobin (HbA$_{1c}$), systolic blood pressure (SBP), diastolic blood pressure (DBP), total cholesterol (TC), LDL cholesterol (LDL-C) and HDL cholesterol (HDL-C). $\textbf{Results:}$ We included seven RCTs with a total of 2277 patients with type 2 diabetes. A range of measures of the consultation was reported, and underlying theory to explain intervention processes was generally undeveloped and poorly applied. There were no overall effects on CVD risk factors; however, trials were heterogeneous. Subgroup analysis suggested some benefit among studies in which interventions demonstrated impact on consultations; statistically significant reductions in HbA$_{1c}$ levels (weighted mean difference, −0.53%; 95% CI: [−0.77, −0.28]; $P$<.0001; $I^{2}$ =46%). $\textbf{Conclusions:}$ Evidence of effect on CVD risk factors from interventions to alter consultations between practitioners and patients with type 2 diabetes was heterogeneous and inconclusive. This could be explained by variable impact of interventions on consultations. More research is required that includes robust measures of the consultations and better development of theory to elucidate mechanisms.HDM was an Academic Clinical Fellow, Andrew Cooper is funded by the University of Cambridge MRC Epidemiology Unit (grant code: MC_UU_12015/4), SJG is an NIHR Senior Investigator. The primary care unit is a member of the National Institute for Health Research (NIHR) School for Primary Care Research and supported by NIHR Research funds. The views expressed are those of the author(s) and not necessarily those of the NHS, the NIHR or the Department of Health