Necrobiosis lipoidica diabeticorum is a rare skin disorder, usually considered a marker for diabetes mellitus. More than half of the patients with necrobiosis lipoidica diabeticorum have diabetes mellitus, but less than one per cent of diabetes mellitus patients have necrobiosis lipoidica diabeticorum. In the diabetes and dermatology literature, we find the position that there is no effect of glucose control on either the appearance of necrobiosis lipoidica diabeticorum or the clinical course of the lesion. We base our challenge to this position on a critical review of the original data. And conclude on the contrary, that necrobiosis lipoidica diabeticorum is usually associated with poor glucose control and that tighter glucose control, as currently practised, might improve or prevent the disorder.