Reduced hyperaemia following skin trauma: evidence for an impaired microvascular response to injury in the diabetic foot.

The hyperaemic response to standard needle injury within dorsal foot skin was investigated in normal and Type 1 (insulin-dependent) diabetic subjects using laser Doppler flowmetry. The normal response was maximal within 15 min, localised, prolonged and biphasic. In 20 normal subjects and three groups of long-duration Type 1 diabetic patients (20 without complications; 20 with laser-treated retinopathy; 15 with neuropathy and retinopathy), the median (interquartile range) peak hyperaemic responses were 1.766 (1.220-1.970), 1.485 (1.342-1.672), 0.997 (0.705-1.203) and 1.030 (0.718-1.369) arbitrary units, respectively. Compared to normal and uncomplicated diabetic groups, peak flow was significantly reduced in the retinopathic (p less than 0.0001) and neuropathic (p = 0.001 and 0.007, respectively) groups. There was no significant difference between the normal and uncomplicated diabetic groups, nor between the retinopathic and neuropathic groups. There was no association of the hyperaemic response with blood sugar, HbA1c, or duration of diabetes. Diabetic patients who have microvascular complications, with or without neuropathy, have an associated impairment of microvascular response to mechanical injury which might predispose to infection and poor wound healing.