Introduction: Prandial insulin is a key component in insulin treatment of type 1 diabetes mellitus (T1DM) and in many patients with type 2 diabetes mellitus (T2DM). The evidence‑based data supporting the choice of an insulin preparation are still limited.

Objectives: We performed a systematic review to summarize and update the evidence on relative efficacy and safety of insulin aspart (IAsp) and regular human insulin (RHI) in both types of diabetes.

Methods: Randomized controlled trials comparing IAsp with RHI in patients with either T1DM or T2DM and conducted until May 2013 were retrieved from a systematic search of MEDLINE, EMBASE, and Cochrane Library.

Results: Of 16 relevant trials, 11 involved patients with T1DM and 5—with T2DM. In the T1DM population, IAsp, when compared with RHI, provided a greater reduction in hemoglobin A1c (HbA1c) levels (weighted mean difference [WMD], –0.11%; 95% confidence interval [CI], –0.16 to –0.05; WMD, –1.2 mmol/mol; 95% CI, –1.7 to –0.5), and improved postprandial glucose levels following breakfast (WMD, –1.40 mmol/l; 95% CI, –1.72 to –1.07), lunch (WMD, –1.01 mmol/l; 95% CI, –1.61 to –0.41), and dinner (WMD, –0.89 mmol/l; 95% CI, –1.19 to –0.59). The risk of nocturnal hypoglycemia was lower in T1DM patients receiving IAsp (relative risk, 0.76; 95% CI, 0.64–0.91), while no difference was observed for severe hypoglycemia. In T2DM patients, IAsp led to a greater reduction in HbA1c levels (WMD, –0.22%; 95% CI, –0.39 to –0.05; –2.4 mmol/mol, –4.3 to –0.5) and postprandial blood glucose. The risk of overall hypoglycemia and severe adverse effects was comparable between the groups.

Conclusions: IAsp provides better glycemic control when compared with RHI in patients with T1DM and T2DM. Fewer T1DM patients treated with IAsp experienced nocturnal hypoglycemia, while both interventions showed a comparable risk of severe hypoglycemic events in both types of diabetes.