BACKGROUND: Telephone interventions are promising for managing glycated hemoglobin A1c (HbA1c) levels in patients with type 2 diabetes mellitus (T2DM). However, optimal follow-up parameters, such as frequency, duration, content, and intervals, are yet to be standardized. This meta-analysis assesses the effectiveness of nurse-led telephone interventions in controlling HbA1c levels, with subgroup analyses based on these variables to provide evidence-based recommendations. METHODS: Searches were conducted across PubMed, Web of Science, Cochrane Library, Embase, Chinese Biomedical Literature Database (CBM), China National Knowledge Infrastructure (CNKI), Wanfang, and China Science and Technology Journal Database (VIP) until February 2024. Study quality was evaluated using Cochrane risk of bias criteria, and data were analyzed with RevMan 5.4. RESULTS: Thirteen studies, including 2,294 T2DM patients, showed that nurse-led telephone interventions significantly reduced HbA1c levels [MD = -0.59, 95% CI (-0.85, -0.34), P <
0.00001, Tau² = 0.15, I² = 87%]. Subgroup analyses indicated that protocols comprising 16 follow-ups [MD = -0.92, 95% CI (-1.71, -0.12), P = 0.02], each lasting 20-25 min [MD = -1.23, 95% CI (-1.63, -0.83), P <
0.001] with half a month intervals [MD = -1.29, 95% CI (-2.43, -0.15), P = 0.03] covering medication, diet, exercise, and glucose monitoring, were the most effective. Protocols involving 12 follow-ups [MD = -0.87, 95% CI (-1.28, -0.46), P <
0.001], each lasting 10-15 min [MD = -0.54, 95% CI (-1.02, -0.06), P = 0.03] at weekly intervals [MD = -0.93, 95% CI (-1.68, -0.17), P = 0.02], also demonstrated significant improvement. Publication bias was assessed using a funnel plot, Egger's Test (P = 0.108), and Begg's Test (P = 0.199), which indicated no significant bias. CONCLUSIONS: Nurse-led telephone follow-ups effectively enhance HbA1c control in T2DM patients. While subgroup findings suggest optimal protocols, individual needs should guide intervention customization. Further high-quality RCTs are needed to validate these results. REGISTRATION NUMBER: PROSPERO: CRD42024578866.