Introduction: The effect of insulin analogues on glycaemic control is well-documented, whereas the effect on avoidance of severe hypoglycaemia remains tentative. We studied the frequency of severe hypoglycaemia in unselected patients with type 1 diabetes treated with insulin analogues, human insulin, or mixed regimens. Methods: A questionnaire was posted from six Danish diabetes clinics to 6112 unselected patients with type 1 diabetes and filled in by 3861 patients (63.2%). Primary endpoint was number of episodes of severe hypoglycaemia in the preceding year. Mild hypoglycaemia was also reported. Results: The frequency of severe hypoglycaemic episodes per patient-year in patients receiving long-acting insulin analogues was 1.47. ±. 0.18 versus 1.09. ±. 0.10 in patients on long-acting human insulin (. p=. 0.01). The frequency of severe hypoglycaemic episodes per patient-year was 1.09. ±. 0.11 in patients on short-acting insulin analogues versus 1.26. ±. 0.13 in patients on short-acting human insulin (. p=. 0.15), which was statistically significant in an adjusted analysis. Conclusions: Severe hypoglycaemia is more frequent in patients with type 1 diabetes treated with long-acting insulin analogues. Confounding by indication may be involved. Clinical intervention trials using insulin analogues in patients prone to severe hypoglycaemia are highly needed.