Insulin glulisine (glulisine), a human insulin analogue with a rapid-acting time-action profile, has been developed to fulfil the mealtime (bolus) insulin requirement in patients with diabetes. The aim of this multinational, multi-centre, controlled, open-label, randomized, parallel-group study was to compare the efficacy and safety of insulin glulisine (glulisine) to that of insulin lispro (lispro) in adults diagnosed with Type 1 diabetes. Of the 683 patients randomized, 672 received treatment (339 patients received glulisine, 333 patients received lispro). Over the 26-week study, a similar reduction in mean HbA1c occurred in both groups (adjusted mean change from baseline -0.14% in both groups). The basal insulin dose was relatively unchanged from baseline in the glulisine group but increased in the lispro group (glulisine: 0.12 IU vs. lispro: 1.82 IU; p = 0.0001). As a consequence, total daily insulin dose decreased in the glulisine group but increased in the lispro group (glulisine: -0.86 IU vs. lispro: 1.01 IU; p = 0.0123). There was no relevant difference between the two groups in the reporting of symptomatic hypoglycaemia (overall, nocturnal and severe). This study demonstrates that glulisine provides equivalent glycaemic control to lispro. The clinical relevance of any difference in total daily insulin dose remains to be established.