Lactose in Type 2 Diabetes
The question of lactose consumption in type 2 diabetes often causes debate. On the one hand, lactose is a carbohydrate (sugar) found in dairy products. On the other hand, dairy foods are an important source of calcium and protein. Let’s take a closer look at how lactose affects the body in diabetes and whether it can be included in the diet.
🧐 What Is Lactose and How Does It Work?
Lactose, also known as milk sugar, is a complex carbohydrate (a disaccharide) composed of two molecules: glucose and galactose. In order for the body to absorb it, the intestine must produce an enzyme called lactase, which breaks lactose down into these simple sugars.
A key feature of lactose is that it:
Is absorbed relatively slowly in the intestine, which helps prevent sharp spikes in blood sugar compared with simple sugars.
Acts as a prebiotic, serving as food for beneficial intestinal bacteria and supporting healthy gut microbiota.
Improves calcium absorption, which is important for bone health.
📊 Effects on Blood Sugar: What Do Studies Say?
For people with type 2 diabetes, it is important to understand how foods affect blood glucose levels. Research suggests that lactose raises blood sugar less than many other carbohydrates.
Glycemic Index (GI): In one study involving people with type 2 diabetes, the glycemic index of lactose was 69 ±10. For comparison, the GI of glucose was 131, while white bread (used as a reference) had a GI of 100. This means the blood sugar response to lactose was about 17% lower than to the same amount of carbohydrates from bread.
Practical conclusion: Lactose does affect blood glucose levels, but it tends to do so more gently and gradually than many other carbohydrate sources.
⚖️ Benefits and Risks: Two Sides of the Coin
Positive Aspects
Nutritional value: Dairy products provide not only lactose but also high-quality protein, calcium, vitamin D, and other micronutrients essential for the body.
Gut microbiota support: Because of its prebiotic properties, lactose can promote the growth of beneficial bacteria such as bifidobacteria.
Potential Risks
Carbohydrate contribution: Even though lactose has a moderate glycemic index, it is still a carbohydrate and must be counted as part of the daily carbohydrate intake.
Individual intolerance: Many people produce less lactase as they age. This may lead to bloating, diarrhea, and digestive discomfort after consuming dairy products. In such cases, lactose-free dairy alternatives may be a better option.
Confusion with lactic acidosis: It is important not to confuse lactose with lactic acidosis. Lactic acidosis is a dangerous condition caused by the accumulation of lactic acid and can occur as a complication of diabetes (especially when certain medications are used). Lactose itself is not directly related to this condition.
🔬 An Unexpected Twist: Milk and Genetics
Recent research has added another interesting perspective. The effect of milk (and the lactose it contains) on diabetes risk may depend on genetics.
A 2024 study published in the journal Nature Metabolism found that in people with genetically determined lactose intolerance (where the lactase enzyme is not active in adulthood), regular milk consumption was associated with a 30% lower risk of developing type 2 diabetes.
Why might this happen? Scientists suggest that in such individuals, undigested lactose reaches the large intestine, where it becomes food for beneficial bacteria such as Bifidobacterium. Changes in gut microbiota composition may positively influence metabolism and reduce diabetes risk.
This finding highlights that the body’s response to lactose can be highly individual.
✅ How to Consume Lactose Safely with Type 2 Diabetes
To make sure dairy products bring benefits without unwanted effects, consider the following recommendations:
Limit the quantity. Some health authorities recommend limiting milk and liquid fermented dairy products to about 100 ml per day in order to control carbohydrate intake.
Choose low-fat products. High fat content in dairy products is undesirable for people with diabetes. Opt for low-fat milk, kefir, and yogurt.
Pay attention to fermented dairy foods. Cottage cheese, cheese, and yogurt contain less lactose than whole milk, because part of it is broken down during fermentation. They are often better tolerated.
Listen to your body. If you experience bloating or abdominal discomfort after drinking milk, it may indicate lactase deficiency. In this case, switching to lactose-free dairy products or plant-based alternatives (such as soy, almond, or oat milk) may help.
Monitor your blood sugar. As with any carbohydrate-containing food, check your body’s response using a glucometer 1–2 hours after consuming dairy products.
Conclusion
Lactose in type 2 diabetes is not forbidden, but it does require attention. It raises blood sugar more slowly than many other carbohydrates and is found in nutritionally valuable foods. The key principles are moderation (about 100 ml of milk per day), choosing low-fat options, and considering individual tolerance.
If you have doubts or specific health conditions, it is best to consult a doctor or dietitian who can help design a diet that suits your individual needs.