Black spots on the skin and diabetes

Some changes arise from insulin resistance, slower healing, altered circulation, infection, or pigment left after inflammation. Unrelated moles, sun-related marks, bruises, and clogged pores remain possible as well.

Acanthosis nigricans presents as darker, thicker, velvety skin, often in body folds such as the neck, armpits, or groin, and can accompany insulin resistance. Diabetic dermopathy presents with small brown, often slightly indented patches, commonly on the shins.

Cuts, blisters, folliculitis, or other inflammation may heal slowly and leave pigment. Reduced sensation can allow a foot injury to go unnoticed, while circulation problems can contribute to colour change; these situations need assessment rather than cosmetic treatment.

Check dark areas in good light, including between the toes and on the soles, and look for cracks, warmth, swelling, discharge, or an open wound. Do not cut a callus, puncture a blister, or apply a strong acid to a dark spot.

If you have diabetes, follow your agreed glucose and foot-care plan and show a new lesion to your healthcare professional. If you have no diagnosis but also notice increased thirst, frequent urination, unexplained weight change, or recurrent infections, arrange medical evaluation and testing.

Seek same-day medical advice for a new foot wound, blister, blackened area, spreading redness, warmth, swelling, pus, or worsening pain, especially if you have diabetes, numbness, or poor circulation. Fever or feeling acutely unwell increases the urgency.

Emergency assessment is appropriate for confusion, unusual drowsiness, vomiting with marked thirst or urination, difficulty breathing, or rapidly worsening tissue colour. Separately, any mole-like spot that evolves, bleeds, or fails to heal needs a skin examination.

Ask whether the change resembles acanthosis nigricans, diabetic dermopathy, infection, impaired circulation, or an unrelated lesion. Clarify whether glucose testing, a foot and circulation examination, dermoscopy, or wound care is appropriate before considering pigment treatment.