Doctors at Peking Union Medical College say: If your fasting blood sugar is normal or slightly elevated, be careful of diabetes!

When you get your physical examination report, obviously unqualified indicators will certainly attract your attention, but those indicators that are within the normal range or only slightly exceeded are often overlooked, and fasting blood sugar value may be one of them. So, does it matter if fasting blood sugar is normal or slightly elevated? An expert from the Department of Endocrinology at Peking Union Medical College Hospital kindly reminds you not to ignore a slight increase in fasting blood sugar, and be careful of diabetes and cardiovascular disease! Let's take a look with me——

About the author: Li Wei

Deputy Chief Physician of the Department of Endocrinology, Peking Union Medical College Hospital. Member of the Standing Committee of the Metabolic Cardiovascular Disease Professional Committee of the Beijing Endocrine and Metabolic Disease Society, member of the Obesity Professional Group of the 10th Committee of the Endocrinology Branch of the Chinese Medical Association, member of the Microvascular Complications Group of the 8th Committee of the Diabetes Branch of the Chinese Medical Association, member of the Youth Working Group of the Adolescent Medicine Professional Committee of the Chinese Medical Doctor Association, and editorial board member of the Chinese Journal of Clinical Physicians.

Diagnostic criteria for diabetes

Once you have symptoms such as thirst, polydipsia, polyuria, polyphagia, and unexplained weight loss, you need to be highly alert to diabetes. At present, the diagnosis of diabetes mainly includes four indicators: fasting blood sugar, 2-hour blood sugar of oral glucose tolerance test (OGTT), glycosylated hemoglobin (HbA1c), and random blood sugar. If typical symptoms of diabetes appear and any of the four indicators is in an abnormal range, diabetes can be diagnosed. The following table shows the diagnostic criteria for diabetes in my country:

1. Fasting state : refers to not eating calories for at least 8 hours;

2. Random blood sugar : refers to the blood sugar at any time of the day without considering the last meal time. It cannot be used to diagnose impaired fasting blood sugar or abnormal glucose tolerance.

The following table shows the classification of glucose metabolism status:

Will the diagnostic indicators for diabetes definitely exceed the standard at the same time?

Although diabetes can be diagnosed if any one of the above indicators is met, for the same diabetic patient, not all four indicators will be exceeded at the same time. The clinical significance of the four indicators has different emphases.

Fasting blood sugar: Relatively stable, not easily affected by diet and exercise in the short term, and can better reflect the amount of liver glycogen output at night.

OGTT 2-hour blood sugar: reflects the pancreatic islet's ability to regulate postprandial blood sugar increase. In the early stages, many patients only show increased postprandial blood sugar, while fasting blood sugar may still be within the normal range. Therefore, this indicator has a better diagnostic sensitivity for patients with prediabetes.

Glycated hemoglobin (HbA1c) : It reflects the average blood sugar level in the last 3 months. It will only increase when both fasting and postprandial blood sugar levels are significantly increased. Therefore, it has good specificity for diagnosing hyperglycemia, but it is not sensitive enough for patients with prediabetes. Other diseases that affect the lifespan of hemoglobin will also affect this indicator.

Random blood sugar: convenient for diagnosing patients whose blood sugar levels have increased significantly.

Simply put, the value of OGTT in diagnosing prediabetes is 2-hour blood glucose > fasting blood glucose > glycated hemoglobin > random blood glucose.

Post-meal blood sugar testing should be taken seriously

Studies have found that the increase in blood sugar after meals is more closely related to the occurrence of diabetic complications . For example, in a European heart survey, more than two-thirds of patients with coronary heart disease had hyperglycemia, of which 28% were prediabetic, 31% were previously known to have diabetes, and 12% were newly diagnosed with diabetes after OGTT was performed after coronary heart disease was discovered. The survey also showed that if OGTT examinations were not performed, about two-thirds of patients with abnormal glucose metabolism would be missed.

Who should be screened for diabetes as early as possible?

People at high risk of diabetes should be screened for diabetes as early as possible.

Adults at high risk include:

(1) History of prediabetes;

(2) Age ≥40 years;

(3) body mass index (BMI) ≥24 and/or central obesity (waist circumference ≥90 cm for men and ≥85 cm for women);

(4) first-degree relatives have a history of diabetes;

(5) Those who lack physical activity;

(6) Women with a history of delivering a macrosomic baby or gestational diabetes;

(7) Women with a history of polycystic ovary syndrome;

(8) Those with acanthosis nigricans;

(9) Those with a history of hypertension or currently receiving antihypertensive treatment;

(10) Those with high-density lipoprotein cholesterol <0.90mmol/L and/or triglycerides >2.22mmol/L, or those who are currently receiving lipid-lowering medication;

(11) History of atherosclerotic cardiovascular disease;

(12) History of steroid use;

(13) Long-term treatment with antipsychotics or antidepressants.

In 2022, the American Diabetes Association (ADA) has advanced the diabetes screening age to 35 years old in its latest diabetes guidelines to address the current trend of younger onset of diabetes.

Children and adolescents at high risk include:

BMI ≥ 85th percentile BMI for the same age and gender, combined with at least one of the following three risk factors:

(1) The mother has diabetes during pregnancy (including gestational diabetes);

(2) first- or second-degree relatives have a history of diabetes;

(3) The presence of clinical conditions associated with insulin resistance (such as acanthosis nigricans, polycystic ovary syndrome, hypertension, dyslipidemia).

If your fasting blood glucose level is between 6.1 and 7.0 mmol/L, or you have the above-mentioned high-risk factors, please promptly undergo an oral glucose tolerance test (OGTT) or go to a regular hospital’s endocrinology department for consultation.

Content from: Dr. Li Weihe said