When discussing skin ageing, we most often think first of the sun, pollution, stress and the natural loss of collagen. However, there is another, often overlooked mechanism quietly acting beneath the surface: glycation. In simple terms, excess sugar in the body affects not only health and metabolism, but can also visibly accelerate skin ageing. Sugar molecules bind to important structural proteins, especially collagen and elastin, making these fibres stiffer, more brittle and less functional. The consequences include fine lines, wrinkles, loss of firmness, reduced skin bounce, sagging and a tired, greyish complexion.

Glycation is a natural, non-enzymatic biochemical process in which sugars and reactive carbonyl compounds bind to proteins, lipids or nucleic acids without enzymatic control. The final products of this process are called advanced glycation end products, or AGEs. Over time, AGEs accumulate in tissues and disrupt the normal function of cells and proteins. In the skin, they are particularly important because they affect long-lived structural proteins of the dermis: collagen, which gives the skin firmness and support, and elastin, which enables elasticity and the skin’s ability to return to its original shape after stretching.

Collagen is the most abundant protein in the skin. It forms a network that gives the skin structure, density and resilience. Elastin allows the skin to return to its original form after facial movement, stretching or pressure. When sugars bind to these fibres, cross-links are formed that make them rigid. Such collagen is harder to remodel, is replaced more slowly by new fibres and is less resistant to mechanical and environmental stress. Glycation is therefore not merely a superficial aesthetic issue, but a process that alters the very architecture of the skin.

Glycation is most often associated with elevated blood glucose levels, which is why it is more pronounced in people with insulin resistance, diabetes or a diet rich in sugars and refined carbohydrates. However, it is not limited to metabolic disorders. AGEs also form in healthy individuals, naturally accumulate with age and are accelerated by diet, UV radiation, smoking, alcohol, stress, lack of sleep and pollution.

An important part of the mechanism involves RAGE receptors – receptors for advanced glycation end products. When AGEs bind to these receptors, oxidative stress, inflammatory processes and degradation of the extracellular matrix are promoted. This creates a vicious circle: more AGEs mean more inflammation and free radicals, while increased oxidative stress further damages collagen, elastin and the epidermal barrier. For this reason, glycation does not only cause wrinkles; it can also contribute to lower skin resilience, dryness, roughness and slower recovery after irritation. (Figure 1)

Figure 1: The effect of AGEs on the epidermis of the skin. (A) AGEs obstruct skin wound healing. (B) AGEs reduce the contents of ceramide (CER) and cholesterol (CHOL) in the epidermis, eventually leading to a reduction in skin lipid content. (C) AGEs destroy the keratinocyte cell structure in the epidermis. (D) AGEs promote the production of melanin in melanocytes. Taken from: Chen CY, Zhang JQ, Li L, Guo MM, He YF, Dong YM, Meng H, Yi F. Advanced Glycation End Products in the Skin: Molecular Mechanisms, Methods of Measurement, and Inhibitory Pathways².

Visible signs of glycated skin often resemble accelerated, premature ageing. The skin may lose elasticity, fullness and firmness, particularly on the cheeks, around the mouth and along the jawline. Fine lines become deeper because rigid collagen fibres tolerate facial movement less effectively and do not renew efficiently. The complexion may appear lifeless, greyish or uneven because AGEs change the quality of the dermal matrix and the skin’s ability to reflect light. The skin may also become more fragile, more sensitive to UV radiation and pollution, and more prone to persistent redness, dryness and a compromised barrier. Slower wound healing is another important consequence, as glycated collagen makes normal tissue regeneration more difficult.

In popular dermatological and aesthetic communication, the term “sugar sag” is sometimes used to describe skin laxity associated with chronic exposure to sugar and accelerated AGE formation. Although simplified, the term captures what happens in the skin: fibres that should be flexible, firm and capable of renewal become stiff, weaker and less functional.

The inside-out approach is based on the idea that skin is cared for not only externally, but also through metabolism. The first step is more stable glycaemia. This means reducing added sugars, sweetened drinks, sweets, white flour and highly processed foods, while increasing the intake of fibre, vegetables, legumes, whole grains, quality proteins and healthy fats. Meals that combine protein, fibre and fats usually lead to a slower rise in blood glucose than meals based almost entirely on refined carbohydrates.

The second step is reducing dietary AGEs. They are produced in larger amounts during frying, grilling, roasting at high temperatures and the formation of a dark, browned crust. Boiling, steaming, stewing, soups and slow-cooked dishes produce fewer AGEs. Marinating foods with lemon, vinegar or herbs before heat treatment may also be a useful strategy. The goal is not to eliminate roasted foods, but to reduce chronic exposure to highly processed, heavily browned and sugar-rich meals.

The third step is a diet rich in antioxidants and polyphenols. Berries, green leafy vegetables, green tea, cocoa, olive oil, rosemary, citrus fruits, nuts and herbs help defend against oxidative stress. This matters because glycation and oxidation reinforce each other. Some compounds, such as carnosine, alpha-lipoic acid, rosmarinic acid, resveratrol and green tea extract, show anti-glycation or antioxidant potential in experimental and partly clinical research. Nevertheless, supplementation should not replace fundamental habits: a high-quality diet, regular movement, good sleep and sun protection.

It is advisable to combine the inside-out approach with targeted skincare.

Antioxidant serums with vitamin C, vitamin E, ferulic acid, niacinamide, resveratrol or green tea may help neutralise free radicals that drive glycation-related damage. Retinoids, derivatives of vitamin A, are important because they stimulate skin renewal, improve texture and support collagen synthesis. Peptides, such as signal peptides in firming formulas, can further support the appearance of elasticity and skin density, especially in combination with retinoids, antioxidants and good hydration.

Carnosine and aminoguanidine are particularly often mentioned in anti-glycation skincare. Carnosine is a dipeptide with antioxidant and anti-glycation potential and is used in some formulas intended to protect collagen from sugar-induced damage. Aminoguanidine is a known inhibitor of AGE formation in experimental models; however, in cosmetic practice, claims should be made carefully and should rely on formulation quality, evidence and safety of use. In other words, an anti-glycation product may be a useful addition, but it is not a replacement for SPF, retinoids, antioxidants and a balanced lifestyle.

Hydration is also important. Well-hydrated skin is more resistant to stressors and better maintains its barrier function. Ingredients such as hyaluronic acid, glycerin and ceramides help retain water, reduce transepidermal water loss and strengthen the skin’s protective layer. Because glycation can compromise the barrier and contribute to dryness and roughness, hydrating care is not merely an aesthetic addition, but part of a strategy to preserve skin resilience.

Sun protection remains essential. UV radiation, especially UVA, accelerates oxidative stress, collagen breakdown and AGE formation. Therefore, daily broad-spectrum sun protection, ideally SPF 30 or higher, is one of the most important measures against glycation-related ageing. An anti-glycation routine without photoprotection remains incomplete.

Professional treatments can additionally help improve skin texture, tone and firmness. Microneedling, chemical peels, laser treatments and collagen-stimulating procedures can support skin remodelling and reduce visible signs of ageing. However, such treatments should be individually adapted to skin type, phototype, barrier condition and any dermatological issues. They do not reverse glycation, but they can improve skin quality when they are part of a broader strategy.

A practical anti-glycation routine can be simple. In the morning: a gentle cleanser, an antioxidant serum, a moisturiser with ceramides or hyaluronic acid and broad-spectrum SPF. In the evening: cleansing, a retinoid or another skin-renewing ingredient, if needed a peptide or anti-glycation formula with carnosine, and a moisturiser to restore the barrier. In sensitive skin, active ingredients should be introduced gradually and without overuse, because an irritated barrier always ages faster.

The most important point is to understand that glycation cannot be completely stopped. It is part of natural ageing. However, its pace can be slowed. Because glycated collagen fibres are difficult to repair, prevention is more important than trying to correct damage afterwards. The best results come from combining daily habits: less added sugar, more stable glycaemia, more antioxidants, less highly processed and heavily browned food, regular physical activity, not smoking, moderate alcohol intake, sufficient sleep, good hydration, barrier-supportive skincare and daily SPF.

Glycation connects nutrition, metabolism and visible skin ageing. It shows that the skin does not age only from the outside in, but also from the inside out. The inside-out approach does not replace dermatological care, retinoids, antioxidants or sun protection; it complements them. The skin is a metabolically active organ. If we want to preserve its elasticity, radiance, firmness and capacity for renewal, an anti-ageing strategy should begin on the plate, in food preparation methods and in everyday lifestyle habits.

This approach does not work as a one-time solution, but as a long-term strategy. Diet and lifestyle habits reduce the internal formation of AGEs, while cosmetic substances applied externally help neutralise oxidative stress, preserve the barrier, stimulate renewal and protect collagen. It is precisely the combination of metabolic balance and targeted skincare that makes the inside-out approach the most logical model for mitigating skin glycation.