In order to evaluate patients with necrobiosis lipoidica diabeticorum and to 
compare them with age, sex, and duration of diabetes matched controls, 15 
patients with necrobiosis were each matched with 5 control subjects with 
diabetes mellitus. Complications of diabetes, glycaemic control, and proteinuria 
were measured. Patients with necrobiosis (mean age 40, range 18-74 years) had a 
mean duration of diabetes of 14 (range 3-36) years; 8 patients were male, and 7 
were female. For necrobiosis versus controls, background retinopathy (67% vs 
27%, p = 0.009), proteinuria (53% vs 17%, p = 0.006), and smoking (60% vs 20%, p 
= 0.003) were all more common with necrobiosis. There were no significant 
differences between patients with necrobiosis and control patients in the 
prevalence of vascular disease and neuropathy. Glycosylated haemoglobin 
concentrations were higher in patients with necrobiosis (p = 0.02). Blood 
pressure measurements were similar in both groups. We conclude that smoking, 
proteinuria, and retinopathy were more prevalent in diabetic patients with 
necrobiosis; the skin lesion may therefore share common aetiological factors 
which affect the microvascular circulation, leading to damage to basement 
membranes and vascular endothelial cells.