PREDICTIVE is a large, multi-national, open-label, prospective, observational study to assess the efficacy and safety of insulin detemir in clinical practice. We report 3-month follow-up data from 389 patients with type 1 (n = 312) and type 2 (n = 77) diabetes from Denmark. Insulin detemir improved glycemic control in type 1 patients, with decreases in mean HbA1c (-0.2%, p = 0.0026), fasting glucose (-1.7 mmol/l, p = 0.0033) and within-patient fasting glucose variability (-0.6 mmol/l, p = 0.0472). Non-significant reductions in glycemic parameters were observed in type 2 patients (-0.3% for HbA1c and -2.7 mmol/l for fasting glucose). There was a decrease in mean body weight in both type 1 and type 2 patients (-0.6 kg, p = 0.025 and -1.0 kg, p = 0.0361, respectively). Three patients (0.8%) reported 4 serious adverse drug reactions, including major hypoglycemia. The incidence of major hypoglycemic episodes was reduced from 3.9/patient-years at baseline to 0.4/patient-years at follow-up in type 1 patients (p < 0.0001), and from 1.0 to 0.0/patient-years in type 2 patients (p = 0.1250). In addition, the mean incidence of total and nocturnal hypoglycemic episodes was reduced in both type 1 (-37.4 and -17.7/patientyears, p < 0.0001 for both) and type 2 patients (-17.7 and -7.8/patient-years, p = 0.0012 and p = 0.0020, respectively). The observations from the Danish cohort of the PREDICTIVE study support the overall findings of PREDICTIVE, i.e. insulin detemir improves glycemic control, with a reduced risk of hypoglycemia and no weight gain.