The Predictable Results and Experience in Diabetes through Intensification and Control to Target: An International Variability Evaluation 303 (PREDICTIVE™ 303) Study (n = 5604) evaluated the effectiveness of insulin detemir, a long‐acting basal insulin analogue, using a simplified patient self‐adjusted dosing algorithm (303 Algorithm group) compared with standard‐of‐care physician‐driven adjustments (Standard‐of‐care group) in a predominantly primary care setting, over a period of 6 months. Insulin detemir was to be started once‐daily as add‐on therapy to any other glucose‐lowering regimens or as a replacement of prestudy basal insulin in patients with type 2 diabetes. Investigator sites rather than individual patients were randomized to either the 303 Algorithm group or the Standard‐of‐care group. Patients from the 303 Algorithm group sites were instructed to adjust their insulin detemir dose every 3 days based on the mean of three ‘adjusted’ fasting plasma glucose (aFPG) values (capillary blood glucose calibrated to equivalent plasma glucose values) using a simple algorithm: mean aFPG < 80 mg/dl (<4.4 mmol/l), reduce dose by 3 U; aFPG between 80 and 110 mg/dl (4.4–6.1 mmol/l), no change; and aFPG > 110 mg/dl (>1.1 mmol/l), increase dose by 3 U. The insulin detemir dose for patients in the Standard‐of‐care group was adjusted by the investigator according to the standard of care. Mean A1C decreased from 8.5% at baseline to 7.9% at 26 weeks for the 303 Algorithm group and from 8.5 to 8.0% for the Standard‐of‐care group (p = 0.0106 for difference in A1C reduction between the two groups). Mean FPG values decreased from 175 mg/dl (9.7 mmol/l) at baseline to 141 mg/dl (7.8 mmol/l) for the 303 Algorithm group and decreased from 174 mg/dl (9.7 mmol/l) to 152 mg/dl (8.4 mmol/l) for the Standard‐of‐care group (p < 0.0001 for difference in FPG reduction between the two groups). Mean body weight remained the same at 26 weeks in both groups (change from baseline 0.1 and −0.2 kg for the 303 Algorithm group and the Standard‐of‐care group respectively). At 26 weeks, 91% of the patients in the 303 Algorithm group and 85% of the patients in the Standard‐of‐care group remained on once‐daily insulin detemir administration. The rates of overall hypoglycaemia (events/patient/year) decreased significantly from baseline in both groups [from 9.05 to 6.44 for the 303 Algorithm group (p = 0.0039) and from 9.53 to 4.95 for the Standard‐of‐care group (p < 0.0001)]. Major hypoglycaemic events were rare in both groups (0.26 events/patient/year for the 303 Algorithm group and 0.20 events/patient/year for the Standard‐of‐care group; p = 0.2395). In conclusion, patients in the 303 Algorithm group achieved comparable glycaemic control with higher rate of hypoglycaemia as compared with patients in the Standard‐of‐care group, possibly because of more aggressive insulin dose adjustments. The vast majority of the patients in both groups were effectively treated with once‐daily insulin detemir therapy. The use of insulin detemir in this predominantly primary care setting achieved significant improvements in glycaemic control with minimal risk of hypoglycaemia and no weight gain.