Diabetes mellitus is a metabolic disorder characterized by a disruption in glucose homeostasis. The most well-known manifestation is that the blood glucose level remains higher than normal. The condition is categorized as Type 1 and Type 2 diabetes. Whilst diabetes can cause many systemic effects, it can also cause certain dermatological complications.
This may occur in any diabetic, but more especially following trauma or injury. This is a common diabetic complication, occurring in 30% of individuals with diabetes mellitus.
The lesions which result are red-brown, roughly round areas of lightly indented, scaly skin. They most often appear on the shins, thus receiving the name ‘shin spots’. Other situations where they are found include certain areas of the thighs, arms, feet, scalp and chest, though less commonly. This harmless condition usually fades over time, as blood glucose levels are appropriately controlled.
The precise cause for this remains undetermined, but there is evidence to suggest an association with diabetic complications – both neuropathic and vascular. In support of this, a high incidence of the condition has been observed in diabetics who also suffer from retinopathy, neuropathy and nephropathy. Furthermore, the condition is most common in patients who are older, or suffer from long-standing diabetes (spanning 10 years or more). There also seems to be a close association with elevated glycosylated hemoglobin, which is indicative of improper long-term blood glucose control.
This type of dermopathy may be a potential indicator of early diabetes. If at least four lesions are present, it is recommended that the patient seek investigation to rule out the development of diabetes.
This non-inflammatory, blistering condition is characterized by the spontaneous occurrence of lesions on the extremities (hands and feet). This is a rare but highly precise indicator of diabetes. It is more common in males than in females, and occurs over a wide age group, of 17-84 years. Additionally, it is more likely to present in patients who have had diabetes for many years, or who suffer any of numerous diabetes-associated complications.
Fortunately, in most cases these bullae heal without requiring treatment. Care should be taken, however, to prevent their bursting so as to avoid secondary infection.
Various type of bullae may be distinguished:
- Intraepidermal bullae: these blisters contain a viscous fluid which is clear and sterile. They ordinarily heal in less than 5 weeks without treatment. Fortunately, no scarring or atrophy results.
- Subepidermal bullae – these present less frequently than the other type of bullosis diabeticorum. Whilst these are similar to intra-epidermal blisters, they differ in that they may contain blood, or, in other words, are occasionally subject to hemorrhage. Following hemorrhage, they may heal with scarring or atrophy of the healed skin.
This is most common in patients suffering from type 1 diabetes of many years’ duration. In this condition, the skin of some joints undergoes a thickening, yellowing change, and also becomes waxy and stiffened. The yellowing is commonly seen on the palms and soles. One possible cause is suspected to be the reaction of glucose with dermal proteins, with an elevated level of glycation products. Some skin proteins such as dermal collagen undergo glycosylation and become yellow.
Thickening of the skin over the hand is also common. This may manifest as mere pebbling of the knuckles to thickened skin over the digits and limited interphalangeal joint mobility, which is called diabetic hand syndrome.