Understand diabetes and the diagnostic criteria for diabetes

As the national "health gatekeeper", primary medical and health institutions undertake more than half of the country's diagnosis and treatment tasks, and 87% of diabetic patients in China are treated in primary medical institutions
.
Therefore, it is the most important
thing for grassroots doctors to correctly grasp the relevant knowledge of diabetes, strictly follow the consultation, examination, diagnosis, set treatment goals, formulate treatment plans, and select treatment drugs.
To this end, we invited Wang Aihong, chief physician of the Strategic Support Force Characteristic Medical Center, to share the relevant content of "Understanding Diabetes and Diagnostic Standards of Diabetes"
.

Normal glucose metabolism

The normal glucose metabolism pathway is to obtain glucose through three pathways: food intake, liver glycogen decomposition and other nutrient conversion, and then catabolize glucose through the three pathways of peripheral tissue oxidative decomposition, liver glycogen synthesis, and conversion into other nutrients, of which hormone regulation is the most important link
to control blood sugar stability.

There are two types of hormones that regulate glucose metabolism, one is hypoglycemic hormone and the other is glycemic hormone
.
Hypoglycemic hormone only insulin, glycemic hormone includes cortisol, epinephrine, glucagon, growth hormone, glucocorticoids, catecholamines and thyroid hormones, of which cortisol, epinephrine, glucagon The three hormones have the most prominent
glycemic effect.
Diagram of normal blood glucose regulation

Insulin is a hormone that promotes anabolism, and its physiological effects are divided into two types: promoting and inhibiting, the main functions are: promoting glucose oxidation, glucose metabolism, and lowering blood sugar; Promote the entry of amino acids, fatty acids, K+, Mg2+ into cells; Promote liver and muscle glycogen synthesis, fat synthesis, protein synthesis
.
Inhibits glycogenolysis, gluconeogenesis, fat or protein breakdown and ketone body production
.

Diagnosis, classification and pathogenesis of diabetes

Diabetes mellitus is a defect in insulin secretion or/or impaired insulin action, resulting in a group of metabolic disorders
characterized by chronic hyperglycemia.
Typical symptoms are "three more and one less", that is, polydipsia, polyphagia, polyuria and weight loss, and other symptoms are itchy skin, dry skin, hunger, blurred vision, tiredness, etc
.
Chronic hyperglycemia can lead to long-term damage, functional defects and failure of multiple tissues, especially the eyes, kidneys, nerves, and cardiovascular diseases, and can cause retinopathy (retinal neovascular fibrous tissue, preretinal hemorrhage, retinal detachment), neuropathy, diabetic foot, skin infections, oral diseases and other complications
.

Natural history of diabetes

In 2011, WHO recommended the use of glycated hemoglobin (HbA1c) to diagnose diabetes in countries and regions where conditions permit, and the diagnostic cut point was HbA1c≥6.
5%.

Therefore, in the 2020 CDS guidelines, China included HbA1c in the diagnostic criteria for diabetes (as shown in the figure below).

If the patient has sickle cell disease, hemodialysis, pregnancy (intermediate or late), recent blood loss or transfusion, glucose-6-phosphate dehydrogenase deficiency, erythropoietin therapy, AIDS, etc.
, diabetes can only be diagnosed based on venous plasma glucose levels
.
In addition, HbA1c screening for cystic fibrosis-related diabetes
is not recommended.

Diabetes is clinically divided into four types: type 1 diabetes (about 5%), type 2 diabetes (accounting for more than 90%), gestational diabetes and special types of diabetes, because type 1 and type 2 diabetes are more common in the clinic, so it is necessary to focus on understanding their characteristics
.

Type 1 diabetes: typical cases occur in children and adolescents, but can occur
at any age.
The onset is acute, prone to ketoacidosis, low plasma insulin levels, must rely on insulin therapy, and autoantibodies are mostly positive
.

Type 2 diabetes: more than adult onset (especially over 45 years of age), most patients have a slow onset and are insidious
in patients.
Plasma insulin relativity and decreased insulin sensitivity may be associated with systemic obesity and abnormal body fat distribution (abdominal obesity), often with a family history, but genetic factors are complex
.

Thus, women with a history of prediabetes, age ≥ 40 years, BMI ≥24 kg/m² and/or central obesity, first-degree relative with a history of diabetes, physical inactivity, macrosomia or gestational diabetes, polycystic ovary syndrome, acanthosis nigricans, hypertension or antihypertensive therapy, HDL cholesterol <0.
90 mmol/L and/or triglycerides >2.
22 mmol/L, or those who are receiving menstrual drug therapy, have a history of atherosclerotic cardiovascular disease, have a history of steroid use, receive antipsychotic drugs or antidepressant drugs for a long time, and have a total score of ≥ 25 points in Chinese diabetes risk score are at high risk of diabetes, and special attention needs to be paid to prevent the occurrence
of diabetes.

OGTT (fasting blood glucose and blood glucose 2 hours after glucose load) is recommended for screening methods for diabetes; If OGTT is difficult, fasting blood glucose alone can be screened, but there is a possibility of missed diagnosis; HbA1c testing is not recommended for routine screening; If the screening results are normal, repeat after 3 years
.

Prevention of diabetes

From 2015 to 2017, the epidemiological survey of thyroid, iodine nutritional status and diabetes mellitus conducted by the Endocrinology Branch of the Chinese Medical Association in 31 provinces showed that the prevalence of diabetes in people aged 18 and above in China was 11.
2%, and the prevalence was still rising.

The awareness rate of diabetes is 36.
5%, the treatment rate is 32.
2%, and the control rate is 49.
2%, which is an improvement from before, but it is still at a low level
.
Among diabetics, type 2 diabetes accounts for more than 90% of the total population, so active prevention of type 2 diabetes is key
.
The key points of tertiary prevention of type 2 diabetes are as follows:

Primary prevention: The purpose is to control the risk factors of type 2 diabetes and prevent the occurrence
of type 2 diabetes.
Patients with prediabetes should be given lifestyle interventions to reduce the risk of developing diabetes (A); Intensive lifestyle interventions, pharmacological interventions may be considered for poor results (B); Diabetes screening for high-risk groups can help detect diabetes early (B).

Secondary prevention: The purpose is to detect early, diagnose and treat patients with type 2 diabetes early and prevent the occurrence
of diabetic complications in diagnosed patients.
OGTT(A) is recommended if fasting blood glucose ≥ 6.
1 mmol/L or random blood glucose ≥ 7.
8 mmol/L; Glycaemic control goals must be individualized (A); For patients with type 2 diabetes mellitus with other cardiovascular risk factors, comprehensive management measures such as hypoglycemia, blood pressure reduction, lipid regulation and aspirin therapy are recommended to prevent the occurrence of cardiovascular disease and diabetic microangiopathy (A).

Tertiary prevention: The goal is to delay the progression of existing diabetes complications, reduce disability and mortality, and improve the quality of life of
patients.
For patients with diabetes with serious complications, treatment in a relevant specialty is recommended (B).