A stable blood sugar level is crucial for our health. Blood sugar levels that are too high or too low can lead to serious health problems in the long term. It is therefore important to know what a normal blood sugar level is and how to regulate it.
What is the normal blood sugar level?
Blood sugar levels are measured in milligrams per deciliter (mg/dL) or millimoles per liter (mmol/L). The normal range for fasting blood sugar is between 70 and 100 mg/dL (3.9 – 5.5 mmol/L). Two hours after a meal, the level should be below 140 mg/dL (7.8 mmol/L). A fasting level of 126 mg/dL or more indicates possible insulin resistance or diabetes and should be monitored further¹.
The World Health Organization (WHO) defines the limit for prediabetes as a fasting blood sugar level between 100 and 125 mg/dl. A value above 126 mg/dl when fasting is considered a warning sign of diabetes². However, blood sugar levels fluctuate depending on the time of day, food intake and physical activity, which is why regular monitoring is advisable.
Why is high blood sugar dangerous?
A permanently elevated blood sugar level (hyperglycemia) can have serious long-term health consequences:
Cardiovascular diseases
High blood sugar levels can lead to arteriosclerosis (hardening of the arteries), which increases the risk of heart attacks and strokes. This disease is caused by damage to the blood vessels caused by the constant increase in blood sugar levels. An increased risk of high blood pressure and impaired blood lipid levels often occur, which puts a considerable strain on the circulatory system.³.
Kidney damage
Excessive blood sugar can cause long-term damage to the kidneys, known as diabetic nephropathy. This can eventually lead to kidney failure if not treated in time. About 30% of people with diabetes develop kidney failure over time, making timely control of blood sugar and treatment of the underlying cause of utmost importance.⁴.
Eye problems
High blood sugar can damage the blood vessels in the eye and lead to diabetic retinopathy, which can cause blindness if left untreated. Early diagnosis and treatment can prevent the disease from progressing.⁵.
Nerve damage
Elevated blood sugar levels can also damage the nervous system and lead to diabetic neuropathy, which causes pain, numbness or tingling in the extremities. Another risk is impaired wound healing, which can lead to foot ulcers - a common cause of amputation in diabetics⁶.
Weakening of the immune system
High blood sugar impairs the immune system and increases the risk of infections. Studies show that poor blood sugar control impairs the body's ability to fight infections, which can lead to serious complications⁷.
What causes high blood sugar levels?
Elevated blood sugar levels can be caused by various factors:
Unhealthy diet
Highly processed foods with lots of sugar and simple carbohydrates cause blood sugar to rise quickly. A diet high in sugar over a long period of time can lead to insulin resistance and, in the long term, diabetes. A balanced diet with fiber and healthy fats can help keep blood sugar stable⁸.
Lack of exercise
Physical activity helps move sugar from the blood into the cells. Too little exercise leads to higher blood sugar levels and can reduce insulin sensitivity⁹.
Insulin resistance
When the body's cells no longer respond properly to insulin, more sugar remains in the blood. This is a typical precursor to type 2 diabetes. A healthy diet and exercise can help improve insulin sensitivity¹⁰.
Stress
Stress hormones such as cortisol stimulate the liver to release more sugar into the blood, which can lead to increased blood sugar levels. Stress management techniques such as relaxation and meditation are therefore important measures for blood sugar control¹¹.
Blood sugar spikes: How quickly does blood sugar rise after a meal?
After eating foods rich in carbohydrates or sugar, blood sugar levels usually rise within 15 to 30 minutes. Foods with a high glycemic index, such as white bread, sweets or soft drinks, in particular, lead to a rapid and sharp rise. The body reacts to this by releasing more insulin to transport the sugar into the cells. This can lead to a sharp drop in blood sugar after about 1 to 2 hours - often accompanied by tiredness, cravings or concentration problems¹².
How can blood sugar spikes be prevented?
Blood sugar spikes can be avoided by a few simple measures:
- Include fiber, protein and healthy fats in your meals:
These nutrients slow down sugar absorption and ensure a more consistent blood sugar response¹³. - Do not eat sweet foods alone:
Consume sugary foods in combination with proteins or fats to reduce the rise in blood sugar. - Note the order of eating:
Studies show that eating vegetables and protein before carbohydrates improves blood sugar control¹⁴. - Regular exercise:
Taking a walk after eating can help reduce blood sugar levels⁹. - Use apple cider vinegar:
A tablespoon of apple cider vinegar in water before a meal can improve insulin response¹⁶.
Does fruit also raise blood sugar?
Fruit sugar (fructose), which is found in fruit, has a different effect on blood sugar than table sugar or refined carbohydrates. This is because fruit naturally contains fiber, water and phytochemicals that slow down the absorption of sugar in the intestine. In addition, fructose is mainly metabolized in the liver and does not directly trigger an insulin response¹⁵.
This means that blood sugar rises less than with glucose or sucrose. When eating fresh fruit, the body also benefits from the nutrients it contains and the more moderate blood sugar reaction.
How can you lower blood sugar naturally in the long term?
Nutrition
A diet rich in fiber and low in sugar and refined carbohydrates is crucial. Whole grains, vegetables, legumes and healthy fats from avocados, nuts and olive oil can help stabilize blood sugar. A balanced diet reduces the risk of developing insulin resistance and diabetes. Special diets, such as the Mediterranean diet, are also known to regulate blood sugar¹³.
Movement
Regular physical activity, such as brisk walking, cycling or swimming, helps the body use sugar more efficiently. Exercise increases insulin sensitivity and lowers blood sugar. Even small changes such as daily walks can have a positive effect on blood sugar.⁹.
Dietary supplements
Some supplements can help regulate blood sugar levels. These include cinnamon, chromium, magnesium, and alpha-lipoic acid. Studies have shown that these supplements can increase insulin sensitivity and stabilize blood sugar levels¹⁷.
Apple cider vinegar
Studies show that apple cider vinegar can help lower blood sugar, especially after meals. A tablespoon of apple cider vinegar diluted in water before or after a meal can lower blood sugar. Apple cider vinegar also has anti-inflammatory properties that may improve insulin sensitivity in the long term.¹⁶.
Inositol
This compound, which is available in certain foods and as a dietary supplement, has positive effects on insulin sensitivity and may help lower blood sugar levels. Studies have shown that inositol is helpful in controlling blood sugar in women with PCOS (polycystic ovary syndrome).¹⁸.
Stress management
Techniques such as yoga, meditation and deep breathing can help reduce stress and stabilize blood sugar levels. Stress reduction promotes insulin production and prevents a sudden release of sugar in the blood.¹¹.
When should you see a doctor?
An increased blood sugar level can indicate diabetes. If symptoms such as constant thirst, frequent urination, tiredness and blurred vision occur, a doctor should be consulted immediately. Regular monitoring of blood sugar levels is also important if you belong to a risk group (e.g. if you are overweight or have a family history of diabetes). An early diagnosis can help to avoid possible secondary diseases¹⁹.
Sources
[1] World Health Organization (WHO): Diagnostic criteria for diabetes.
[2] American Diabetes Association: Blood sugar levels and their meaning.
[3] Kannel WB et al., "Blood glucose and cardiovascular disease", Journal of Cardiology.
[4] National Kidney Foundation: Diabetes and Kidney Health.
[5] Cheung N et al., “Diabetic Retinopathy,” The Lancet.
[6] Vinik AI et al., “Diabetic Neuropathy,” Endocrinology & Metabolism Clinics.
[7] Geerlings SE et al., “Effect of hyperglycemia on immune function,” Current Diabetes Reports.
[8] Ludwig DS et al., “The glycemic index and diabetes risk,” JAMA.
[9] Colberg SR et al., “Physical Activity and Insulin Sensitivity,” Diabetes Care.
[10] Petersen MC et al., “Insulin Resistance Mechanisms,” Cell Metabolism.
[11] Hackett RA et al., "Stress and glucose metabolism", Psychoneuroendocrinology.
[12] Holt SH et al., “The glycemic response to carbohydrate-rich foods,” American Journal of Clinical Nutrition.
[13] Reynolds A et al., “The role of fiber in glycemic control,” The Lancet.
[14] Shukla AP et al., “Food Order and Glycemic Control,” Diabetes Care.
[15] Livesey G, “Fructose metabolism and glycemic response”, American Journal of Clinical Nutrition.
[16] Mitrou P et al., "Vinegar consumption and insulin sensitivity", European Journal of Clinical Nutrition.
[17] Anderson RA et al., “Chromium and glucose metabolism,” Diabetes.
[18] Nestler JE et al., “Inositol and PCOS-related insulin resistance,” New England Journal of Medicine.
[19] International Diabetes Federation: Symptoms and diagnosis of diabetes.