How Blood Sugar May Affect Your Skin

How blood sugar may affect your skin

Acne doesn’t come from eating greasy food. But what we eat can influence some of the biological pathways involved in acne.

Foods with a high glycaemic load cause a rapid rise in blood glucose and insulin. This can increase signalling through insulin-like growth factor 1 (IGF-1), a pathway involved in sebum production, androgen activity and the growth of skin cells within the follicle. Together, these effects may make blocked and inflamed follicles more likely.

Clinical studies suggest that a lower-glycaemic-load diet can improve acne in some people, although the evidence is not strong enough to consider diet a treatment on its own.

What a functional approach looks at

A functional approach doesn’t replace conventional acne treatment. Instead, it asks whether there are modifiable factors that may be contributing to the problem.

• Diet — particularly a high-glycaemic-load diet. This has some of the better dietary evidence in acne, although studies are still relatively small.
• Hormones — androgens are central to acne biology. Hormonal influences may be particularly relevant in women with premenstrual flares, adult-onset acne or other signs of androgen excess.
• Nutritional status — zinc has some evidence as an adjunctive treatment, particularly for inflammatory acne. Evidence for omega-3 fatty acids is interesting but much more preliminary.
• Gut health — there is increasing interest in the gut–skin axis and the ways in which the intestinal microbiome may influence inflammation and immune signalling. The science is promising, but we don’t yet have enough evidence to prescribe a particular “gut treatment” for acne.
• The skin microbiome — acne is not simply an infection caused by having too much Cutibacterium acnes. Different strains of the bacterium, their relationship with other skin microorganisms and the way the immune system responds to them all appear to matter.

What does the evidence actually show?

Diet: probably relevant, but not the whole story

Among nutritional factors studied in acne, high-glycaemic-load diets have some of the most convincing evidence. Several studies suggest that reducing rapidly absorbed carbohydrates may improve acne, potentially through effects on insulin and IGF-1 signalling.

Dairy is more complicated. Observational studies have found associations between acne and milk consumption, particularly skimmed milk, but this doesn’t prove that milk causes acne. If there is an effect, milk proteins and their influence on insulin/IGF-1 signalling may be more relevant than the fat content.

So there is no universal “acne diet.” But for someone eating a diet dominated by sugar and refined carbohydrates, improving dietary quality is a reasonable part of a broader treatment plan.

The microbiome: acne is more complicated than “bad bacteria”

Our understanding of C. acnes has changed considerably. The bacterium lives normally on healthy skin, so acne isn’t simply caused by acquiring an infection. Research increasingly points towards differences in microbial balance, particular C. acnes strains and the immune response they provoke.

Antibiotics can alter the skin and gut microbiomes and contribute to antimicrobial resistance, which is one reason prolonged antibiotic treatment for acne is discouraged. But claims that antibiotics simply “wipe out the good bacteria” or that we currently know how to “rebuild” the acne microbiome go beyond the evidence.

Probiotics are being investigated as a possible adjunct. Some trials are encouraging, but results remain inconsistent and we don’t yet know which strains, doses or treatment durations are most useful.

Zinc: useful, but not a miracle mineral

People with acne have, on average, been found to have lower serum zinc levels than people without acne. A systematic review and meta-analysis also found that zinc treatment can reduce inflammatory papules.

That makes zinc an interesting adjunct, particularly where dietary intake or zinc status is low. But it isn’t a substitute for effective acne treatment, and more isn’t necessarily better: excessive zinc supplementation can cause gastrointestinal symptoms and, over time, copper deficiency.

Omega-3: promising rather than proven

Omega-3 fatty acids have anti-inflammatory effects and there is emerging evidence that they may benefit some people with acne. Small clinical studies have reported improvements, but the evidence base is still too limited to call omega-3 an established acne treatment.

A Mediterranean-style eating pattern rich in vegetables, pulses, whole grains, nuts, fish and unsaturated fats is nevertheless a sensible way of improving overall dietary quality without turning meals into a pharmaceutical regime.

Hormones matter, but “hormonal acne” doesn’t always mean abnormal hormones

Androgens stimulate sebaceous glands and are fundamental to acne development. This is also why treatments that reduce androgen signalling can be highly effective in appropriate women.

Premenstrual flares and persistent adult female acne can suggest a strong hormonal component. However, acne around the jawline does not automatically mean that someone’s hormones are abnormal.

Hormonal investigation is most useful when acne occurs alongside features such as irregular periods, hirsutism, androgenic hair loss or other signs suggesting androgen excess or conditions such as PCOS.

Natural products marketed as “hormone balancing” deserve more caution. Saw palmetto, for example, has potential anti-androgenic activity, but there is insufficient clinical evidence to recommend it as an established treatment for acne.

Where a functional approach has limits

A thoughtful functional assessment might include looking at diet, medications, previous antibiotic exposure and menstrual or hormonal patterns, and investigating nutritional deficiencies or endocrine abnormalities where there is a clinical reason to do so.

What it shouldn’t mean is ordering an enormous panel of tests in every person with acne. Many commercial microbiome, food-sensitivity and “hormone balance” tests have not been adequately validated for diagnosing the cause of acne. An abnormal-looking laboratory result isn’t necessarily the reason someone is breaking out.

And none of this should delay effective treatment for moderate, severe or scarring acne. Preventing permanent scarring matters far more than pursuing the perfect zinc level or microbiome profile.

What to expect

The best way to think about a functional approach is as an additional layer of acne care, not an alternative universe of acne medicine.

Addressing a high-glycaemic diet, a genuine nutritional deficiency or a relevant hormonal disorder may improve acne and support conventional treatment. Gut and skin microbiome interventions are exciting areas of research, but they are not yet established replacements for proven therapies.

Acne is rarely caused by one thing. The useful question isn’t “What is my one root cause?” but: “Which of the factors driving acne are relevant to me, and which of them can we realistically change?”

That is where a genuinely personalised approach becomes useful.

Sources

• Baldwin H, Tan J. Effects of Diet on Acne and Its Response to Treatment. Am J Clin Dermatol. 2021;22(1):55–65.
• Bhate K, Williams HC. Epidemiology of acne vulgaris. Br J Dermatol. 2013;168(3):474–485.
• Dréno B, Dagnelie MA, Khammari A, Corvec S. The Skin Microbiome: A New Actor in Inflammatory Acne. Am J Clin Dermatol. 2020;21(Suppl 1):18–24.
• Sánchez-Pellicer P, Navarro-Moratalla L, Núñez-Delegido E, et al. Acne, Microbiome, and Probiotics: The Gut–Skin Axis. Microorganisms. 2022;10(7):1303.
• Guertler A, Neu K, Lill D, et al. Exploring the potential of omega-3 fatty acids in acne patients: A prospective intervention study. J Cosmet Dermatol. 2024;23(10):3295–3304.
• Yee BE, Richards P, Sui JY, Marsch AF. Serum zinc levels and efficacy of zinc treatment in acne vulgaris: A systematic review and meta-analysis. Dermatol Ther. 2020;33(6):e14252.
• Searle T, Ali FR, Al-Niaimi F. Zinc in dermatology. J Dermatolog Treat. 2022;33(5):2455–2458.

General information only, not medical advice. A functional approach to acne is meant to complement, not replace, care from a qualified dermatologist or doctor. Discuss any supplement or diet change with your practitioner, especially if you take other medication.