Skin infections are common in patients with diabetes. Bacterial infections are likely to occur in the form of boils, carbuncles or styes and are usually associated with a staphylococcal infection. Candida albicans is associated with oral or vaginal thrush and intertrigo in the groins or breasts. Tinea infection is also more common and presents with tinea pedis, tinea cruris, tinea corporis or chronic paronychia. These problems should respond to antibiotics or antifungals. It may be necessary to follow-up with a fasting blood sugar.
Warning signs of atherosclerosis are hairless, dry and scaly skin and thickened nails. Toes are usually affected first but the gangrene may extend to the foot. Doppler ultrasound will help to measure the severity of the arterial disease and indicate whether sympathectomy or arterial reconstruction would be possible. If all else fails, amputation may be necessary.
Generalised Granuloma Annulare
Granuloma annulare (GA) is a problem that occurs in children and young adults where lesions affect the hands, fingers or feet. Generalised GA is sometimes associated with diabetes mellitus. The patient presents with yellow, red or brown macules and papules over the trunk and limbs. A skin biopsy will confirm the condition. Treatment is not usually required but in widespread or troublesome cases topical, intralesional or systemic steroids, isotretinoin, methotrexate, psoralen and UVA and phototherapy are possible.
Ischaemic changes that develop as the result of atherosclerosis in diabetes may cause problems with ulcers on the feet that fail to heal. Additional factors are related to peripheral neuropathy and patients may fail to notice injuries because of sensory loss. This patient with uncontrolled diabetes was unaware of this ulcer between the toes until seen at a routine check. Secondary infection of these lesions is a risk. Regular supervision and adequate foot care is important.
The cause of necrobiosis lipoidica may be due to a diabetic microangiopathy. It may present in patients with an abnormal glucose tolerance test or a family history of diabetes. The patient presents with red-brown patches that have a waxy appearance, telangiectasia and an atrophic centre which can break down and ulcerate. Treatment tends to be unsatisfactory but topical steroids under occlusion or intralesional steroids may help. Some success has been reported with a combination of aspirin and dipyridamole. Excision and grafting have been also used.
Diabetic dermopathy tends to occur in older patients with long-standing diabetes. The cause of the condition is unknown but is linked to an increased glycosylated haemoglobin and poor diabetes control. The patient presents with painless, non-itchy, round and brown or reddish scaly lesions, usually on both shins. Any patient with such a rash, if not already diagnosed, should be investigated to exclude diabetes. No specific treatment is required as the lesions tend to resolve spontaneously, especially if better control of the diabetes is achieved.