Many skin conditions are associated with diabetes, and some are more likely to appear in the earlier stages of the disease. While you may not suspect diabetes simply because of a skin manifestation, being aware of them can help form an overall picture of a patient’s situation.
Herein, George Han, MD, PhD, describes the most common – and most relevant for physicians – skin conditions that may be associated with early stages of diabetes. Dr. Han is an associate professor in the department of dermatology at the Donald and Barbara Zucker School of Medicine at Hofstra/Northwell in Hempstead, NY.
Skin Disorders Common with Diabetes
Diabetic Dermopathy
These “shin spots,” which are brownish discoloration in smudgy spots on the anterior shins, are probably the most common skin finding in people with diabetes, though some people without diabetes may also get similar findings. “For darker skin types, [shin spots] would still appear as hyperpigmented but the exact hue may be more dark purplish/deep brown - it's rather subtle sometimes but we do see it across all skin tones,” Dr. Han explained. There is a questionable connection between prior unnoticed trauma (unnoticed, perhaps, because of a coexisting peripheral neuropathy) and subsequent post-inflammatory hyperpigmentation and cutaneous atrophy worsened by diabetes and poor blood supply.
Acanthosis Nigricans
Thickened plaques in the body folds are common but reflect localized insulin resistance in the skin, so AN is mechanistically linked to diabetes. When there is no underlying known diabetes, the presence of AN may prompt an endocrinologic evaluation (endocrine conditions such as Cushing’s syndrome or polycystic ovary syndrome [PCOS] have also been associated with AN). Rarely, it can indicate an underlying malignancy (specifically, adenocarcinoma of the GI tract).
Scleredema Diabeticorum
Also known as diabetic thick skin, scleradema diabeticorum can have signs that range from asymptomatic skin thickening to limited mobility (cheiroarthropathy) when the affected skin is over the joints. It has been estimated that 8% to 36% of patients with insulin-dependent diabetes develop some form of skin thickening, but it can also affect patients with non-insulin-dependent diabetes.
Yellow Nails
Often, patients come in with yellow nails thinking it is fungus; however, especially in people with diabetes who are older, there can be a characteristic yellowing of the nails, reported to affect up to 40% of individuals with diabetes.
“The nails may look different [in patients of color] because of underlying pigment but the yellow hue would still be present - the main challenge here is distinguishing from onychomycosis, or nail fungus,” Dr. Han said. There is a mechanistic link to diabetes here, which is the role of glycation end-products in yellowing the skin. Another nail finding may be onychorrhexis, which is longitudinal ridging of the nails.
“Importantly, though, another condition features the same color – called yellow nail syndrome,” he added. “The latter can actually be related to pulmonary issues, so it's important to make sure we're not missing anything.”
In addition to these commonly seen skin conditions, Dr. Han noted that there is a litany of other related conditions, including necrobiosis lipoidica and granuloma annulare, which have demonstrated some connection with diabetes.
Although many skin disorders may co-occur with diabetes, “there isn’t any one specific skin finding that should make someone think, ‘This patient may have diabetes,’” he clarified, adding that other, more noticeable factors such as central adiposity are probably of higher relevance.
More Clues to Diabetic Skin Links
Additional research into the connections between diabetes and skin manifestations is needed because “none of our associations are sensitive enough to really correlate with clinical clues,” Dr. Han said. What is needed, he suggested, is the finding of a skin symptom of diabetes that improves as the diabetes is under better control, or conversely, worsens as the diabetes worsens.
Dr. Han noted that one possible area of research would be to study cohorts of patients with psoriasis and diabetes and examine whether diabetic control can be improved concurrently with the treatment of psoriasis.
“Interestingly, the mechanisms underlying psoriasis, such as increased IL-17, have also been implicated in a hyperinflammatory state in diabetes, with the lowering of IL-17A levels leading to reduced hyperglycemia in an animal model,” he explained.
“So, there is a lot of work to do in the future, but some intriguing connections are already being made.”
Disclosures: Dr. Han reported no conflicts.