Aims: The aim of the trial was to compare the efficacy and safety of the new, long-acting basal insulin, insulin glargine (LANTUS®), with NPH human insulin, each administered in a combination regimen with oral antidiabetic drugs in patients with Type 2 diabetes. Methods: In a multicentre, open, randomised study, 570 patients with Type 2 diabetes, aged 34 - 80 years, were treated for 52 weeks with insulin glargine or NPH insulin given once daily at bedtime. Previous oral antidiabetic therapy was continued throughout the study. Results: There was a clinically relevant decrease in glycosylated haemoglobin (GHb) values from baseline to endpoint with both drugs (insulin glargine: - 0.46 %; NPH insulin: - 0.38 %; p = 0.415); also, this difference was statistically significant in the subgroup of overweight patients with BMI > 28 kg/m2 (insulin glargine: - 0.42 %, NPH insulin: - 0.11 %; p = 0.0237). Over the entire treatment period, NPH insulin-treated patients (41 %) and insulin glargine-treated patients (35 %) experienced a similar level of symptomatic hypoglycaemia. A statistically significant difference was observed in the number of patients treated with NPH insulin who reported at least one episode of nocturnal hypoglycaemia compared with those treated with insulin glargine in the overall population and in the overweight subgroup (overall: 24 % vs. 12 %, p = 0.002; overweight: 22.2 % vs. 9.5 %, p = 0.0006), using the Cochran-Mantel-Haenszel test. These differences were most pronounced in insulin-naïve and overweight (BMI > 28 kg/m2) sub-groups. The incidence of adverse events was similar for the two treatments. Conclusions: This study demonstrated that insulin glargine is as effective as NPH insulin in achieving glycaemic control in patients with Type 2 diabetes, and is associated with fewer episodes of symptomatic hypoglycaemia, particularly nocturnal episodes.