Can you really tell if someone has high blood sugar by looking at their face?
Can you really look at someone’s face and tell if their blood sugar is high? Social media seems to think so. A red patch beside the nose, darkened skin, a fungal rash or even a few skin tags can quickly become “proof” of diabetes in an Instagram diagnosis.
But that logic has a problem: your face cannot give you a blood sugar reading.
“Diabetes and the face: please stop diagnosing diabetes from someone’s nose,” Dr Rajiv Kovil, Diabetes & Obesity Specialist at Zandra Healthcare clarifies.
“Social media has created a dangerous new genre of medicine: look at a photograph, identify a patch of skin, and announce that somebody has diabetes. That is not diagnosis. That is conjecture dressed up as medicine.”
So, are there any changes on the skin that should make you think about blood sugar?
That red patch beside your nose is not a diabetes test. One of the claims doing the rounds online is that redness or a rash around the sides of the nose means someone’s blood sugar is high. It doesn’t.
“There is no medically recognised ‘red nose-crease sign’ that diagnoses high blood sugar or diabetes,” Dr Kovil says.
Redness and scaling around the folds beside the nose are common and can have several causes. One possibility is seborrhoeic dermatitis, which frequently affects the scalp, eyebrows, glabella and nasolabial folds and is associated with the normal skin yeast Malassezia. Rosacea, contact or irritant dermatitis and other inflammatory conditions can also cause similar changes.
“If the person has genuine diabetes risk factors, test for diabetes—but test because of the risk, not because somebody on social media inspected their nose,” Dr Kovil says.
The skin can drop hints about insulin resistance
This is where some genuine medicine meets the social-media chatter.
Certain skin changes can act as clues that a person may need a metabolic check-up. One of the more important ones is acanthosis nigricans. It appears as darkened, thickened, velvety skin, particularly around the neck and body folds, and can indicate significant insulin resistance even before diabetes develops.
“Sometimes the skin provides clues; it does not provide a glucose reading. Recognised diabetes-associated findings include acanthosis nigricans, recurrent bacterial or fungal infections, diabetic dermopathy, necrobiosis lipoidica, eruptive xanthomas and, less commonly, diabetic bullae. Acanthosis nigricans—dark, thickened, velvety skin, particularly around the neck and body folds—is particularly useful because it may indicate significant insulin resistance even before diabetes develops. But none of these replaces laboratory testing.”
Skin tags can also accompany insulin resistance and type 2 diabetes.
“A dermatologist or physician recognises a phenotype and then investigates the biology behind it. A rash is not an HbA1c,” Dr Kovil says.
That distinction matters: a skin clue is not a diabetes diagnosis.
What about fungal infections? There is some truth here
“Sometimes the skin provides clues; it does not provide a glucose reading. Recognised diabetes-associated findings include acanthosis nigricans, recurrent bacterial or fungal infections, diabetic dermopathy, necrobiosis lipoidica, eruptive xanthomas and, less commonly, diabetic bullae. Acanthosis nigricans—dark, thickened, velvety skin, particularly around the neck and body folds—is particularly useful because it may indicate significant insulin resistance even before diabetes develops. But none of these replaces laboratory testing.”
Skin tags can also accompany insulin resistance and type 2 diabetes.
“A dermatologist or physician recognises a phenotype and then investigates the biology behind it. A rash is not an HbA1c,” Dr Kovil says.
That distinction matters: a skin clue is not a diabetes diagnosis.
What about fungal infections? There is some truth here
People with poorly controlled diabetes can be more susceptible to infections, including Candida or yeast infections. These may occur in moist skin folds, the mouth and genital areas.
But the reason is much more complicated than the viral claim that sugar feeds fungus.
“Higher glucose concentrations in certain tissues or secretions can favour Candida growth, adhesion and colonisation. But diabetes-associated susceptibility to fungal infection involves much more: altered innate and adaptive immunity, impaired neutrophil function, changes in epithelial defence and microbiota, vascular disease and local environmental factors such as moisture and friction.”
A recurrent or unusually persistent fungal infection can therefore be a reason to investigate for diabetes. But the infection itself does not prove that someone’s blood sugar is high.
“It contains a fragment of truth wrapped in a major oversimplification,” Dr Kovil says of the “sugar feeds fungus” claim. “Moreover, finding a fungal rash does not prove that the person’s glucose is high—people without diabetes develop fungal infections every day.”
As he puts it, “Medicine becomes misinformation when a complex association is reduced to ‘rash = fungus = sugar = diabetes.’ Human biology simply does not work like a social-media infographic.”
Your eyelids can offer clues too
There are legitimate metabolic clues around the eyes, but they need interpretation too.
Xanthelasma, for example, appears as yellowish plaques, often near the inner parts of the eyelids. It represents lipid-laden cells in the skin and can point towards dyslipidaemia and broader cardiometabolic risk. It can occur with diabetes, but also in people without diabetes or even without abnormal routine lipid levels.
Xanthelasma—yellowish plaques, often near the inner aspects of the eyelids—represents lipid-laden cells in the skin and should prompt consideration of dyslipidaemia and broader cardiometabolic risk
“Xanthelasma—yellowish plaques, often near the inner aspects of the eyelids—represents lipid-laden cells in the skin and should prompt consideration of dyslipidaemia and broader cardiometabolic risk; it can occur with diabetes but also in people without diabetes or even without abnormal routine lipid levels.”
Recurrent styes and some infections may also occur more frequently with diabetes. However, some of the most important eye complications of diabetes are inside the eye, particularly diabetic retinopathy, rather than something that can be diagnosed by examining an eyelid in a selfie.
So which skin changes are actually worth checking?
Besides acanthosis nigricans and skin tags, recurrent fungal or bacterial infections, persistent itching or dry skin, poorly healing wounds and recognised conditions such as diabetic dermopathy can justify metabolic evaluation.
Another important clue is eruptive xanthomas, which appear as sudden crops of yellowish-red papules and can indicate severe hypertriglyceridaemia, sometimes alongside uncontrolled diabetes.
These findings are worth discussing with a doctor rather than turning them into an internet diagnosis.
So, can you diagnose diabetes by looking at someone’s face?
No. “You cannot diagnose diabetes from a red nose crease, pigmentation, a fungal rash, skin tags or somebody’s photograph,” Dr Kovil says.
Diabetes is a biochemical diagnosis, made using validated criteria involving plasma glucose and/or HbA1c, with appropriate confirmation depending on the clinical circumstances.
A skin finding may be enough for a doctor to think the person’s metabolic health should be checked. It is not enough for someone scrolling through Instagram to announce that another person has diabetes.
“A skin finding may make a competent physician think, ‘Perhaps I should check this patient’s metabolic health.’ It should never make somebody declare, ‘You have diabetes because I looked at your face.’ That isn’t early diagnosis. It is bad medicine masquerading as medical insight.”