Note: The third testing method OGTT

Note: The third testing method (OGTT) is not recommended for routine clinical use. During diagnosis, if any one of the above three criteria is abnormal and confirmed by repeat testing on another day, diabetes can be diagnosed. Table 5: Classification of Diabetes Etiology Type 1 diabetes: Destruction of pancreatic β cells, often leading to absolute insulin deficiency and a tendency toward ketoacidosis. Type 2 diabetes: Primarily insulin resistance, accompanied by relative insulin deficiency, or insulin secretion defects coupled with insulin resistance. Type 3 specific diabetes

1. Diabetes caused by genetic defects in pancreatic β cell function;
2. Diabetes caused by defects in insulin action genes or insulin receptor genes;
3. Diabetes caused by exocrine pancreatic diseases, including pancreatitis, pancreatic trauma or resection, pancreatic cysts, cystic fibrosis, hemochromatosis, fibrocalcific pancreatic disease, etc.;
4. Diabetes caused by endocrine diseases: including acromegaly, Cushing's syndrome, glucagonoma, pheochromocytoma, hyperthyroidism, growth hormone tumor, aldosterone tumor, etc.;
5. Drug-induced or chemical-induced diabetes: including nicotinic acid, glucocorticoids, thyroid hormones, diazoxide, β-adrenergic antagonists, thiazide diuretics, phenytoin, etc.;
6. Infection-induced diabetes: including congenital rubella virus, cytomegalovirus, etc.;
7. Uncommon immune-regulatory diabetes;
8. Other genetic diseases sometimes accompanied by diabetes. Type 4 gestational diabetes

IV. Differential Diagnosis (1) Liver Disease Carbohydrate metabolism mainly takes place in the liver, so patients with liver disease often experience metabolic disorders that lead to reduced glucose tolerance. At the same time, liver disease causes abnormal liver function, reducing insulin inactivation in the liver and thus affecting normal carbohydrate metabolism. Hepatitis viruses can invade

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Pancreatic β cells are damaged, leading to impaired β-cell function and the development of diabetes. Typically, as liver function recovers in most patients with liver disease, their glucose tolerance tests gradually return to normal. (II) Chronic Kidney Disease Chronic kidney disease can cause tubular reabsorption dysfunction, resulting in polydipsia, polyuria, and glucosuria, which leads to renal glycosuria. In addition, renal dysfunction can cause electrolyte disturbances, leading to intracellular potassium deficiency and impairing insulin release, thereby reducing glucose tolerance. (III) Stress State When the human body experiences severe infection, trauma, extensive burns, severe poisoning, myocardial infarction, cerebral hemorrhage, cerebral infarction, severe pain, massive blood loss, severe dehydration, or severe hypoxia, a stress response occurs. Through the cerebral cortex–pituitary–adrenal system, this triggers the massive secretion of adrenal cortical hormones and adrenaline. These hormones have an antagonistic effect on insulin, thus causing transient hyperglycemia and reduced glucose tolerance. (IV) Endocrine Diseases In patients with acromegaly, excessive growth hormone secretion counteracts (antagonizes) the effects of insulin, leading to pituitary glycosuria; Cushing's syndrome can cause glycosuria due to excessive secretion of adrenal cortical hormones; pheochromocytoma can secrete large amounts of adrenaline and noradrenaline, promoting hepatic glycogenolysis and gluconeogenesis, thereby increasing blood glucose; and patients with hyperthyroidism, due to enhanced systemic metabolism, promote glucose absorption and utilization, sometimes also leading to elevated blood glucose. (V) Simple Obesity Obese individuals or those with obesity have higher baseline insulin levels than normal people. Additionally, adipocytes have relatively fewer insulin receptors on their membranes, reducing insulin affinity. This results in insulin resistance, which can sometimes lead to elevated blood glucose. (VI) Patients with Chronic Diseases Due to prolonged bed rest and reduced physical activity in patients with chronic diseases, or due to hunger and malnutrition, the body's compensatory insulin secretion decreases, weakening the ability of tissues to utilize glucose. Both of these factors can lead to decreased glucose tolerance test results. (VII) Medications Some patients who take adrenal cortical hormones, salicylates such as aspirin, thiazide diuretics like hydrochlorothiazide for long periods may experience elevated blood glucose and glucosuria. After discontinuing these medications, blood glucose levels can gradually return to normal. Chapter 2: Treatment of Diabetes Section 1: Dietary Therapy Dietary therapy for diabetes, also known as medical nutrition therapy, is one of the foundational treatments for diabetes and should be consistently followed throughout the patient's lifetime. The essence of dietary therapy is to control the condition by appropriately adjusting the "quality" and "quantity" of food intake. Traditional Chinese medicine has long emphasized the role of dietary therapy in treating diseases. The "Plain Questions · Discussion on the Timing of Organ Qi" states: "Poisonous medicines attack pathogenic factors, grains nourish, fruits assist, meats benefit, and vegetables fill." The "Plain Questions · Discussion on Bi" further clarifies: "Excessive eating damages the stomach and intestines." During the Tang Dynasty, Sun Simiao wrote in the "Qianjin Fang": "Anyone who drinks excessively over a long period will inevitably develop diabetes. The foundation of health lies in diet... Those who do not know how to eat properly cannot maintain life." He also explicitly stated: "A physician must first understand the root cause of the disease and identify its specific manifestations, then treat it through diet. If dietary therapy fails, only then should medication be prescribed." In the Ming Dynasty, Zhang Jingyue pointed out in the "Complete Works of Jingyue": "The onset of diabetes is always related to the consumption of rich, greasy foods and the harm caused by alcohol, sex, and overwork." These discussions highlight the general principles of diet: one should avoid long-term overconsumption of high-nutrient, high-calorie foods, excessive oily foods, and picky eating. All nutrients should be consumed in appropriate proportions to meet the body's needs and promote health. (1) The Role of Dietary Therapy in Diabetes

1. Reducing the Burden on the Pancreas As mentioned earlier, long-term nutritional excess leads to excessive caloric intake, increasing the burden on the pancreas. At the same time, high-calorie diets easily cause obesity, which in turn leads to insulin resistance, further exacerbating the burden on the pancreas. Therefore, dietary therapy can both ensure that patients receive all necessary nutrients without overburdening the pancreas, thereby helping to alleviate and control the condition. Approximately 80% of type 2 diabetic patients are initially obese due to nutritional excess and reduced physical activity, which worsens insulin resistance. Consistent dietary therapy can reduce excess fat, maintain a standard weight, and help control blood glucose levels.
2. Correcting Metabolic Disorders Dietary therapy ensures that the food consumed meets the body's nutritional needs, helping to bring excessively high blood glucose back to normal. It also allows for adjustments to the diet based on the patient's condition, which can help lower high blood lipids and improve protein deficiencies. Furthermore, dietary therapy can improve abnormalities in blood coagulation and fibrinolysis, helping to prevent or delay complications such as cardiovascular and cerebrovascular diseases, kidney disease, retinal lesions, and neuropathy.
3. Reducing Postprandial Hyperglycemia Consuming an appropriate amount of fiber-rich foods, such as bran, rice bran, corn husks, vegetables, wild greens, and seaweed, can slow down the intestinal absorption of postprandial carbohydrates, thereby lowering postprandial blood glucose. In addition, fiber-rich foods can also lower blood lipids and prevent constipation.
4. Improving Patient Constitution Dietary therapy not only ensures that patients receive the necessary calories from their basic diet but also calculates daily caloric needs based on the patient's workload and level of physical activity. For children, adolescents, pregnant women, lactating mothers, the elderly, thin individuals, and diabetic patients with complications, caloric intake can be adjusted according to individual circumstances to determine the amounts of carbohydrates, proteins, and fats in the diet that affect blood glucose changes. In this way, the body's normal needs are met while reducing the burden on pancreatic β cells, effectively correcting metabolic disorders, and strengthening the constitution of diabetic patients. (2) Misconceptions About Dietary Therapy
5. Starvation Therapy This is a one-sided understanding of dietary therapy, believing that the less staple food diabetic patients eat, the better. As a result, patients are kept in a state of prolonged hunger or semi-starvation, depriving their bodies of essential nutrients and worsening their condition. Patients are prone to hypoglycemic reactions, or, due to insufficient calorie supply, their bodies begin to consume fat and protein, producing large amounts of ketones and triggering ketoacidosis.
6. Unrestrained Eating Overeating and reduced physical activity leading to obesity are among the causes of diabetes. If diabetic patients do not control their diet, it will further burden already damaged pancreatic β cells, rapidly worsening the condition and causing various acute and chronic complications that threaten the patient's life. Therefore, diabetic patients should appropriately limit total caloric intake and adjust the proportion of different food groups to reduce the burden on pancreatic β cells and bring carbohydrate, protein, and fat metabolism closer to normal.
7. Improper Dietary Control Some diabetic patients mistakenly believe that dietary control means restricting only staple foods like rice and noodles, while ignoring soy products, meat, eggs, and cooking oil, or using fruits and buckwheat as substitutes for meals. This leads to increased blood glucose and weight gain, further aggravating the condition. Although the main source of blood glucose is staple food, proteins and fats in side dishes are also converted into glucose after entering the body, raising blood glucose levels. Moreover, this can increase blood lipids and body weight, making the condition worse. (3) How to Choose a Diet
8. Choosing Food Quantity Food quantity refers to the total calories a patient consumes each day. It should fully consider the capacity of the patient's pancreatic β cells while also meeting the needs of normal growth and development as well as daily work and life activities. The standard for maintaining weight is to keep it within ±5% of the standard weight. If it exceeds this standard, total calories should be appropriately reduced; if it falls below this standard, total calories can be appropriately increased.
9. Proportion of Dietary Composition The general principle is to formulate a "reasonable, balanced, and scientific" dietary structure. However, each patient must flexibly tailor it according to their specific condition, stage of the disease, and individual eating habits and lifestyle. (1) Carbohydrates: Under the premise of keeping total calories constant, a diet with a higher proportion of carbohydrates is appropriate. Generally, carbohydrates should account for 50%–65% of total calories, and in some cases even up to 85%. However, for patients with fasting blood glucose >11.1 mmol/L, the proportion of carbohydrates should still be appropriately limited. Food choices should primarily focus on rice and noodle-based staples, which can make up two-thirds of total carbohydrates, with the remaining one-third consisting of fruits, potatoes, vegetables, etc. It is also advisable to consume some fiber-rich foods, such as fruits, vegetables, [seaweed]{.underline}, laver, beans, and whole grains, which not only improve postprandial hyperglycemia but also help lower blood lipids. (2) Protein: Diabetic patients should appropriately increase protein intake, aiming for 12%–20% of total calories. For children, pregnant women, malnourished thin individuals, or patients with chronic wasting diseases such as tuberculosis and chronic hepatitis, protein intake in the diet can be appropriately increased. When diabetes is complicated by kidney disease but renal function has not yet failed, protein content in the diet can also be appropriately increased, preferably animal protein. Sodium intake in the diet should be limited, ideally to 6 g of salt per day. However, when kidney function has declined, patients should follow a low-protein diet, with protein accounting for about 10% of total calories. The ratio of plant-based to animal-based protein intake for diabetic patients should be 2:1. Plant-based protein mainly comes from grains and legumes, while animal-based protein includes fish, poultry, eggs, and dairy products. Animal protein is high-quality protein, rich in essential amino acids. If the body lacks essential amino acids, even with sufficient protein intake, negative nitrogen balance may occur, which is detrimental to health. Therefore, essential amino acids are very important for health and recovery from illness. There are eight essential amino acids: lysine, methionine, valine, leucine, isoleucine, threonine, phenylalanine, and tryptophan. For infants and young children, histidine should also be added. The types and quantities of amino acids contained in dietary protein should be as close as possible to the body's needs to maximize its physiological value (see Table 6). Generally speaking, the diabetic diet should Table 6: Essential Amino Acids in Common Foods

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Food | Tryptophan | > Phenylalanine | Lysine | Threonine | Methionine | > | | Isoleucine | Valine | | | | | | > Leucine | | Japonica Rice | > 1.61 | > 4.86 | > 4.00 | > 3.99 | > 2.06 | > 9.08 | > 3.46 | > 4.15 Indica Rice | > 1.68 | > 5.75 | > 3.92 | > 3.85 | > 1.65 | > 8.40 | > 3.54 | > 3.94 Small Rice | > 1.92 | > 5.69 | > 1.93 | > 4.14 | > 2.88 | > 14.86 | > 3.59 | > 6.35 White Corn | > 0.77 | > 5.15 | > 3.65 | > 4.61 | > 1.85 | > 15.38 | > 3.28 | > 4.20 Sweet Potato | > 1.41 | > 5.20 | > 6.17 | 5.65u | > 1.41 | > 7.90 | > 3.58 | > 1.12 Potato | > 2.10 | > 5.90 | > 8.30 | > 6.90 | > 2.50 | > 9.60 | > 3.70 | > 5.30 Soybean | > 1.22 | > 4:94 | > 6.57 | > 4.28 | > 4.06 | > 4.94: | > 3.91 | > 4.93 Broad Bean | > 0.68 | > 3.93 | > 6.44 | > 4.06 | > 0.56 | > 8.06 | > 3.42 | > 4.46 Pea|Bean | > 0.83 | > 5.59 | > 7.44 | > 3.85 | > 1.00 | > 7.39 | > 3.41 | > 4.63 Green Bean | > 1.07 | > 6.50 | > 7.40 | > 4.30 | > 1.33 | > 9.53 | > 4.06 | > 5.92 Red Bean | > 0.70 | > 5.43 | > 7.55 | > 4:32 | > 1.21 | > 9.09 | > 3.67 | > 5.01 Ensure adequate protein intake, at a level comparable to or slightly higher than that of healthy individuals. To enhance the practical value of protein, the diet should combine meat and vegetables, mix grains and vegetables, and pair coarse and fine grains to leverage the complementary effects of different food sources.

(3) Fat: Fat is an important structural component of the human body, protecting and stabilizing internal organs. It is also the primary source of energy, with 1 g of fat providing 37.62 kJ of energy—twice as much as the same amount of protein or carbohydrates. In addition, essential fatty acids such as linoleic acid cannot be synthesized by the body and must be obtained through diet, while fat-soluble vitamins like vitamins A, D, E, and K can only be absorbed and utilized when fat is present. However, diabetic patients often experience disruptions in sugar and fat metabolism, leading to reduced fat synthesis and accelerated fat breakdown, which increases blood lipids and promotes atherosclerosis, accelerating the development of complications. Therefore, fat intake should be adjusted according to the patient's condition. Generally, daily intake should account for 20%–35% of total calories, with obese patients needing to reduce it further. The preferred types of fat are vegetable oils such as soybean oil, corn oil, sesame oil, mustard oil, and peanut oil, as these oils contain more unsaturated fatty acids, which can lower blood lipids and prevent atherosclerosis. It is best to minimize or avoid animal fats and foods high in cholesterol, such as animal offal, egg yolks, and fish roe.

(4) Dietary Fiber: According to clinical research, soluble dietary fiber can improve sugar metabolism, lower cholesterol, reduce blood glucose, and enhance insulin sensitivity. Foods rich in soluble fiber include fruits containing pectin, seaweed and laver containing alginate, and konjac containing konjac gum. Therefore, the diet should include an appropriate amount of fruits, seaweed, laver, bran, and other foods high in soluble fiber.