Telephone calls and glycemic control in type 2 diabetes: A PRISMA-compliant systematic review and meta-analysis of randomized clinical trials

Aims In-depth and updated systematic reviews evaluating telephone calls in type 2 diabetes (T2DM) management are missing. This study aimed to assess the effect of this intervention on glycemic control in T2DM patients when compared with usual care. Methods We systematically searched for randomized controlled trials (RCT) on T2DM using Medline, Embase, Cochrane Central Register of Controlled Trials, Cumulative Index to Nursing and Allied Health Literature (CINAHL), and LILACS, up to March 2021. The Risk of Bias 2.0 (Rob 2.0) tool and GRADE were used for the quality evaluation. The intervention effect was estimated by the change in glycated hemoglobin (HbA1c). PROSPERO registry CRD42020204519. Results 3545 references were reviewed and 32 were included (8598 patients). Telephone calls, all approaching education, improved HbA1c by 0.33% [95% CI, -0.48% to -0.18%; I-2 = 78%; p < 0.0001] compared to usual care. A greater improvement was found when the intervention included pharmacologic modification (-0.82%, 95% CI, -1.42% to -0.22%; I-2 = 92%) and when it was applied by nurses (-0.53%, 95% CI, -0.86% to -0.2%; I-2 = 87%). Meta-regression showed no relationship between DM duration and HbA1c changes. Conclusion The telephone call intervention provided a benefit regarding T2DM glycemic control, especially if provided by nurses, or if associated with patient education and pharmacological treatment modification.