The aim of this study was to evaluate the weight change from baseline while using insulin detemir in subjects with type 2 diabetes mellitus under normal clinical practice conditions. It was a multicentre, open label, non-randomised, non-interventional, observational, safety and efficacy study in subjects using insulin detemir for the treatment of type 2 diabetes mellitus. In this study, the mean body weight decreased marginally by -0.8 kg at the end of week 26 from baseline. Change in mean body weight during the study was not statistically significant (p > 0.05). There was a statistically significant (p < -0.05) change in waist circumference (-0.7 cm) from baseline at week 26. Mean fasting plasma glucose reduced significantly (p < 0.0001) from 199.1 mg/dl at initiation of insulin detemir to 141.3 mg/dl at week 13 and 115.8 mg/dl at week 26. Mean HbA1c reduced significantly (p < 0.0001) from 9.2% at initiation of insulin detemir to 7.8% at week 13 and 7.2% at week 26. Insulin dose changed marginally from the baseline (15.1 units) to week 26 (15.3 units). Majority of the subjects (89%) were on once daily insulin detemir. Before initiating insulin detemir proportion of subjects experiencing at least one episode of hypoglycaemia during the past four weeks was 8.8% (n = 884). It was reduced 2.4% (n = 241) at week 13 and 1.6% (n = 164) at week 26 following initiation of insulin detemir. There were no major nocturnal hypoglycaemic episodes during 26 weeks of insulin detemir therapy. In conclusion, this study indicates that insulin detemir is safe, effective and weight neutral.