Five Stages of Diabetes: Analysis of Blood Glucose Changes and Complication Progression

Diagnostic Criteria for Diabetes: The sole criterion for diagnosing diabetes is blood glucose. Blood glucose, or glucose in the blood, is one of the body's energy sources. Normal fasting blood glucose (FBS) for adults is 3.6–6.1 mmol/L, and 2-hour postprandial blood glucose (20-hour postprandial blood glucose) is 3.6–7.7 mmol/L.

When measuring blood glucose, it is important to note that fasting blood glucose should be measured within 12 hours; 2-hour postprandial blood glucose is measured from the first bite of food.

Symptoms of Diabetes: A fasting blood glucose level ≥7.8 mmol/L, or a blood glucose level greater than or equal to 11.1 mmol/L at any time, is sufficient for a diagnosis of diabetes.

Symptoms of Diabetes but Normal Blood Glucose: If symptoms of diabetes are present but blood glucose levels do not meet the above criteria, a glucose tolerance test should be performed. For adults, after ingesting 75 grams of glucose on an empty stomach, blood glucose is measured 2 hours later. A blood glucose level greater than or equal to 11.1 mmol/L is diagnostic of diabetes; a blood glucose level less than 7.8 mmol/L is considered normal; and a blood glucose level between 7.8 and 11.1 mmol/L indicates hypoglycemia.

No symptoms of diabetes: In addition to the above two diagnostic criteria, several additional criteria are needed to confirm whether a person has diabetes.

(1) After ingesting 75 grams of glucose, blood glucose is measured 1 hour later. A blood glucose level greater than or equal to 11.1 mmol/L is required.

(2) Fasting blood glucose is greater than or equal to 7.8 mmol/L.

(3) After ingesting 75 grams of glucose on an empty stomach, blood glucose is measured 2 hours later. A blood glucose level greater than or equal to 11.1 mmol/L is required.

If all the above tests are met, diabetes can be diagnosed.

Traditional Chinese Medicine (TCM) classifies diabetes into four stages: Prediabetes (Stage I), Symptomatic Diabetes (Stage II), Early Complications (Stage III), Mid-Complications (Stage IV), and Severe Complications (Stage V).

Stage I (Prediabetes): In prediabetes, patients are often overweight or obese with a strong appetite. They may appear healthy, but their energy and physical strength are diminished, making them feel weak and unable to perform tasks effectively. At this stage, there are no typical diabetic symptoms, but the patient has already entered the prediabetic stage. Fasting blood glucose is normal or slightly elevated, but postprandial hyperglycemia and glycosuria occur. Oral glucose tolerance tests are abnormal, blood lipids are mostly high, and stage I hypertension is present.

Stage II (Symptomatic Diabetes): When patients progress to Stage II, typical diabetic symptoms begin to appear, such as polydipsia, polyuria, polyphagia, weight loss, and fatigue. During this stage, blood glucose, urine glucose, and glycosylated hemoglobin are all elevated, blood lipids are mostly high, and hypertension is present, but no other vascular or neurological complications occur.

Stage III (Early Stage of Complications): In the early stage of complications, clinical vascular and neurological complications will appear. Stage III is defined by any of the following: early neuropathy, retinopathy stages I-II, early diabetic nephropathy, and possible macrovascular complications such as hypertension, coronary heart disease, and lower extremity vascular disease.

Stage IV (Mid-Stage of Complications): If diabetic retinopathy stages III-V, clinical diabetic nephropathy progressing to renal decompensation, diabetic cardiomyopathy progressing to cardiac decompensation, and typical diabetic neuropathy manifestations such as limb numbness and pain, muscle atrophy, intractable diarrhea, impotence, and neurogenic bladder appear, then the stage of complications has been reached. This stage is characterized by yin deficiency and qi and yang depletion, blood stasis in the collaterals, and phlegm and blood stasis. It requires serious attention and meticulous treatment; otherwise, progression to the late stage will be life-threatening.

Stage V (Late-Stage Complications): When complications progress to the late stage, the condition becomes dangerous and can be life-threatening if not treated promptly. This stage is characterized by severe organ damage or organ/limb disability. Any of the following conditions qualifies as late-stage complications: diabetic retinopathy leading to blindness; diabetic nephropathy progressing to uremia; diabetic cardiomyopathy resulting in acute myocardial infarction; severe arrhythmia; heart failure or even sudden death; diabetic complications leading to acute cerebrovascular disease; severe diabetic gangrene of the extremities, etc.