During a check-up, a call comes from the practice: The fasting blood sugar is at 108, and the long-term value is at 5.9 percent. This is not diabetes, but it is also not healthy in the strict sense. This intermediate range is called prediabetes. It usually remains asymptomatic, and that’s exactly why it’s worth knowing about: This is where the most can be done.
What “Prediabetes” Really Means
The body keeps blood sugar levels within a narrow corridor. Insulin transports sugar from the blood into the cells. When insulin’s effectiveness weakens, the pancreas has to produce more, and eventually, it’s not enough to keep sugar levels low after meals or overnight. The values rise but remain below the threshold for diabetes.
Experts refer to this as impaired fasting glucose or impaired glucose tolerance, depending on the measurement method. Both are risk states, not a disease in the sense of diabetes. However, they indicate that the metabolism is using up reserves.
Which Values Are Considered Concerning
The thresholds vary slightly between professional societies. Commonly, as per the classification of the American Diabetes Association and German practice recommendations, these ranges are:
- Fasting blood sugar (at least eight hours without food): 100 to 125 mg/dl, equivalent to 5.6 to 6.9 mmol/l. The WHO sets the lower limit at 110 mg/dl.
- HbA1c, the “long-term value”: 5.7 to 6.4 percent.
- Glucose tolerance test, value two hours after 75 grams of glucose in water: 140 to 199 mg/dl.
From 126 mg/dl fasting, from 6.5 percent HbA1c, or from 200 mg/dl in the tolerance test, the guidelines refer to diabetes. The diagnosis is made by the doctor not based on a single value but after confirmation, provided there are no clear symptoms.
By the way, a single value is not a judgment. After a sleepless night, an infection, or a hearty dinner, the number may look different the next morning. Therefore, in case of abnormalities, measurements are usually repeated.
Why It Often Goes Unnoticed
Tiredness after lunch, cravings for sweets, a tightening belt: Many experience this, even with completely normal sugar levels. Typical diabetes signs like excessive thirst or frequent urination only appear at significantly higher levels. In prediabetes, it is usually silent.
A clue can come from the skin. Dark, velvety discolorations on the neck or in the armpits (acanthosis nigricans) occur with pronounced insulin resistance. They are not a definitive proof but a reason to have blood sugar tested.
Who Should Get Tested
The risk significantly increases in certain situations:
- Overweight, especially with a lot of fat around the abdomen
- Diabetes in parents or siblings
- High blood pressure or abnormal blood fats
- History of diabetes during pregnancy
- Little physical activity, predominantly sedentary lifestyle
- Older age
Legally insured individuals are entitled to a health examination, the “check-up,” every three years starting at age 35. This includes a blood sugar measurement. Those in one of the risk groups can also address this with their doctor earlier. If blood pressure has been an issue before, the topic is relevant: How to tackle it is outlined in Lowering Blood Pressure in Daily Life, much of which also helps with blood sugar.
What Studies Show: The Course Is Not Set in Stone
Prediabetes is not a one-way street. In the American Diabetes Prevention Program Study, a lifestyle change reduced the risk of developing type 2 diabetes by 58 percent within nearly three years compared to the control group. Participants aimed for about seven percent less body weight and engaged in around 150 minutes of physical activity per week. A Finnish study reached the same conclusion, also with a 58 percent reduction.
These are study groups with support, and things don’t always go smoothly in daily life. However, the direction is correct: Small, sustainable changes are more effective than a big resolution that fizzles out by February.
Counteracting Without Overhauling Daily Life
Weight: A Few Kilos Often Suffice
It’s not about ideal weight. Even a five to seven percent reduction, which means about four and a half to six kilos at 90 kilograms, significantly improves insulin sensitivity. More important than the method is that you can maintain it for a year. Strict diets that lead to weight regain are not very effective.
Exercise: Better Frequent Than Heroic
The WHO recommends that adults engage in at least 150 to 300 minutes of moderate activity per week. Those who have not been active for a while can start with ten minutes of walking after meals. Muscles then take up sugar even without much insulin. Strength training twice a week complements this. An example of how to start is shown in Movement Instead of Bed Rest: Exercises for Back Pain; the basic idea applies here too: better regular and moderate.
Diet: Less Sugary Drinks, More Fiber
The biggest lever is often beverages: soda, juice, sweetened coffee. After that, whole grains instead of white flour, legumes, vegetables, and nuts are worthwhile. No bans are necessary. A dessert on Sunday doesn’t change much, but a daily soft drink does.
Sleep, Stress, Smoking
Those who consistently sleep too little are more likely to develop insulin resistance, and stress hormones drive blood sugar up. More on this in the article Sleep Medicine: Healing for Sleep Disorders and Ways to Restful Sleep. Smoking additionally increases diabetes risk, and quitting is beneficial here as well.
And Medications?
In certain cases, doctors may discuss medication support, especially at very high risk. This is decided on a case-by-case basis. Taking pills on your own or using supplements that are supposed to “regulate blood sugar” does not help anyone.
How Often to Check?
Prediabetes should not just be diagnosed and then forgotten. Regular checks are common, about once a year, and more frequently if at high risk. How often exactly is determined by the practice. Make a note of the appointment, as it can easily be forgotten without symptoms.
When You Should See a Doctor Promptly
Have your blood sugar checked promptly if you experience unusual thirst for weeks, urinate very frequently, lose weight unintentionally, feel constantly tired, notice poorly healing wounds, or have recurrent infections. These can be signs of manifest diabetes.
You need immediate medical help, in an emergency call 112, if you experience severe nausea with vomiting and abdominal pain, noticeably deep, rapid breathing, confusion, or altered consciousness with known high blood sugar.
Frequently Asked Questions
Does Prediabetes Always Progress to Diabetes?
No. The risk is increased, but there is no automatic progression. For some affected individuals, values normalize again after changes in weight, activity, and diet.
Is a Single Measurement Sufficient for Diagnosis?
Usually not. Doctors confirm concerning values with a second measurement or another method, such as the HbA1c value in addition to fasting blood sugar.
Can I Measure Blood Sugar at Home?
It is technically possible with a fingerstick device. However, for diagnosis, laboratory measurements count. Home values can be confusing if you don’t know how to interpret them. Discuss this with your practice beforehand.
Can People with Prediabetes Still Eat Sweets?
Yes, in moderation. What matters is what dominates daily life. Sugary drinks and large amounts of white flour products daily harm blood sugar more than a piece of cake on the weekend.
Also Read
- Diabetes and Metabolic Disorders: Causes, Effects, and Prevention Strategies
- Overweight and Obesity: Effective Therapies for a Healthier Life
- Lowering Blood Pressure in Daily Life: Salt, Exercise, and Weight
This article is for informational purposes only and does not replace medical advice.
Sources
- American Diabetes Association Professional Practice Committee: Classification and Diagnosis of Diabetes, Standards of Care in Diabetes. Diabetes Care 2024;47(Suppl 1).
- World Health Organization / International Diabetes Federation: Definition and diagnosis of diabetes mellitus and intermediate hyperglycaemia. Report of a WHO/IDF consultation, Geneva 2006.
- Knowler W. C. et al.: Reduction in the incidence of type 2 diabetes with lifestyle intervention or metformin (Diabetes Prevention Program). New England Journal of Medicine 2002;346(6):393–403.
- Tuomilehto J. et al.: Prevention of type 2 diabetes mellitus by changes in lifestyle among subjects with impaired glucose tolerance. New England Journal of Medicine 2001;344(18):1343–1350.
- World Health Organization: WHO guidelines on physical activity and sedentary behaviour. Geneva 2020.