AIM: We aim to evaluate the effects of biphasic insulin compared with a basal bolus insulin regimen on glycaemic control, total daily insulin requirements, risk of hypoglycaemia, weight and quality of life in patients with diabetes mellitus. METHODS: MEDLINE, EMBASE, PubMed and Scopus databases were searched for studies up to November 2013. Interventions that lasted for more than four weeks and were reported in English were considered for the review. Meta-analysis was performed on eligible studies. RESULTS: Fifteen randomized controlled trial studies, involving 4384 patients, were included. Greater HbA1c reductions were seen with basal-bolus compared with biphasic insulin regimens, between-treatment weighted mean difference (WMD) for baseline-to-endpoint changes in HbA1c was -0.2% (95% CI: -0.36 to -0.03) [-2.2 (-3.9, -0.3) mmol/mol]. In non-insulin naïve (n = 8) patients with Type 2 diabetes, HbA1c reduction was greater in the basal bolus group; WMD = -0.22% (95% CI: -0.42 to -0.02) [-2.4 (-4.6, -0.2) mmol/mol], but in insulin naïve patients (n = 5), HbA1c was equivalent between the two regimens; WMD (-0.15% (95% CI: -0.52 to 0.22) [-1.6 (-5.7, 2.4) mmol/mol]. Total daily insulin requirements and weight were increased with both regimens, whereas hypoglycaemia rates were comparable between the two regimens. Greater HbA1c reduction was observed in the basal bolus group compared with the biphasic regimen at the expense of higher daily insulin requirements and weight gain, but with no greater risk of hypoglycaemia. CONCLUSIONS: Biphasic and basal bolus regimens were equally effective in reducing HbA1c in insulin naïve patients with Type 2 diabetes and both regimens are equally effective for initiating insulin in Type 2 diabetes.