Standards of care for type 2 diabetes in China

The past 30 years have witnessed significant increases in the prevalence of type 2 diabetes mellitus (T2DM) in China. A 1980 epidemiological survey that included 30 000 people from 14 provinces and cities nationwide indicated that the prevalence of diabetes was 0.67% 1. A 1994–1995 epidemiological survey that included 210 000 people from 19 provinces and cities found that the prevalence of diabetes was 2.5% among individuals who were 25–64 years old (with a population standardized rate of 2.2%) and that the prevalence of impaired glucose tolerance was 3.2% (with a population standardized rate of 2.1%) 2. A national nutrition survey conducted in 2002, showed that the prevalences of diabetes were 4.5% and 1.8% among people over 18 years in the urban and rural areas, respectively 3. In 2007–2008, the Chinese Diabetes Society (CDS) performed an epidemiological survey in 14 provinces and cities nationwide. After adopting a weighted analysis that took into account factors such as gender, age, rural and urban distributions and regional differences, the estimated prevalence of diabetes was 9.7% in adults over 20 years of age in China 4, accounting for 92.4 million adults with diabetes (43.1 million rural residents and 49.3 urban residents) (Table 1). This guideline recommends the World Health Organization's (WHO) (1999) the criteria for diagnosis and classification of diabetes, and classification of metabolic status (Table 2): either the fasting plasma glucose (FPG) or the 2-h plasma glucose (2-h PG) value after a 75-g oral glucose tolerance test (OGTT) can be used alone for epidemiological investigations or mass screenings 7. However, the data in China include only the FPG levels, resulting in a larger proportion of diabetes being missed. The ideal investigation should simultaneously check FPG and 2-h PG after the glucose load; blood glucose levels at other time points after the OGTT are not used as diagnostic criteria. Individuals with impaired fasting glucose should undergo the OGTT to reduce the number of missed diabetes diagnoses. The 2010 American Diabetes Association guidelines added glycated haemoglobin (HbA1c) ≥6.5% as a diagnostic criterion for diabetes 8. In 2011, the WHO also recommended that wherever conditions permit, countries and regions may consider adopting this cut-off point for diabetes diagnosis 9. However, given that the HbA1c test is not yet commonly applied in China, the insufficient degree of standardization, and the fact that the instruments and quality control for measuring HbA1c are currently unable to meet the current diagnostic standard for diabetes, this guideline does not recommend the use of HbA1c for diagnosis of diabetes in China. Nevertheless, for hospitals that use a standardized HbA1c assay with a normal reference value of 4.0–6.0% and strict quality control, HbA1c ≥6.5% can be used as a reference when diagnosing diabetes. This guideline adopts the diabetes aetiology classification system proposed by the WHO (1999), which divides diabetes into four major categories based on aetiological evidence, that is, T1DM, T2DM, gestational diabetes mellitus (GDM) and special types of diabetes. The goal of primary prevention is to prevent the occurrence of T2DM. Secondary prevention aims to prevent diabetic complications in patients with T2DM. Tertiary prevention aims to delay the progression of diabetic complications, to reduce morbidity and mortality and to improve the patients' quality of life. The risk of T2DM depends primarily on the patient's number and degree of risk factors. Some of these factors cannot be changed, whereas others can (Table 3). Primary prevention efforts for T2DM should adopt hierarchical management approaches based on the differences between the high-risk population and general population. It is not feasible either to screen prediabetes in the entire Chinese population or to systematically identify high risk groups by blood glucose tests, considering the huge population in China. Therefore, the identification of high-risk groups relies primarily on opportunistic screening (e.g. screening that occurs during routine physical examinations or during treatment for other diseases). Screening of diabetes benefits the early diagnosis of diabetes and improves the prevention and treatment of diabetes and its complications. Therefore, when conditions permit, high-risk groups should be targeted for diabetes screening. Definition of the high-risk diabetes group among adults are as follows: adults (>18 years) with one or more of the following diabetes risk factors: (1) age ≥40 years, (2) history of impaired glucose regulation, (3) overweight (BMI ≥24 kg/m2) or obesity (BMI ≥28 kg/m2) and/or central obesity (male waist circumference ≥90 cm and female waist circumference ≥85 cm), (4) sedentary lifestyle, (5) first-degree relatives with T2DM, (6) women who delivered a baby weighing ≥4 kg) or were diagnosed with GDM (7) hypertension [systolic blood pressure ≥140 mmHg and/or diastolic blood pressure ≥90 mmHg (1 mmHg = 0.133 kPa)] or on therapy for hypertension, (8) dyslipidemia [high-density lipoprotein cholesterol (HDL-C) ≤0.91 mmol/L (≤35 mg/dL) and triglycerides ≥2.22 mmol/L (≥200 mg/dL)] or on therapy for hyperlipidemia, (9) atherosclerotic cardiovascular disease, (10) a transient history of steroid diabetes, (11) polycystic ovary syndrome and (12) long-term use of antipsychotics and/or antidepressant treatment. Of the aforementioned factors, impaired glucose regulation is the most important high-risk factor: approximately 5%–10.0% of patients with impaired glucose tolerance progress to T2DM annually 10. For adults in the high-risk group, diabetes screening should be performed as early as possible, regardless of age; for populations with no diabetes risk factors other than age, screening should begin at ≥40 years of age. For children and adolescents at a high risk for diabetes, screening should begin at age 10 years; however, for individuals with an earlier onset of puberty, this guideline recommends that screening starts at puberty. Those whose initial screening results are normal are recommended to undergo screening again at least once every 3 years. At medical institutions with a qualified laboratory, diabetes screening is recommended for high-risk patients during their visits or physical examinations. The fasting blood glucose test is a simple diabetes screening method that should be used for routine screening, albeit there's risk of missing diagnosis. When conditions permit, the OGTT (both FPG and 2-h PG after glucose load) should be performed as often as possible. HbA1c testing is not currently recommended as a routine screening method. To improve the effectiveness of diabetes screening for the general population, targeted diabetes screening should occur according to the individual's degree of diabetes risk. Multiple randomized and controlled studies have shown that people with impaired glucose tolerance can be delayed or prevented from developing to T2DM, through appropriate lifestyle interventions, 11-13. In a study conducted in Daqing, China, patients in the lifestyle intervention group were asked to increase vegetable intake and reduce intake of alcohol and monosaccharides, and those who were defined as overweight or obese (BMI >25 kg/m2) were encouraged to lose weight, increase intensity of physical activity by performing at least 30 min of moderately intense activity per day. After a 6-year lifestyle intervention, the cumulative incidence of T2DM risk for the subsequent 14 years decreased by 43% 14. The lifestyle intervention groups in the Finnish Diabetes Prevention Study 15 and the American Diabetes Prevention Program 16 also demonstrated that the intervention could significantly reduce the risk of developing T2DM among patients with impaired glucose tolerance. This guideline recommends that patients with prediabetes lower the risk of diabetes through diet control and exercise; that patients should receive regular follow-up that provides psychosocial support to ensure patients' long-term adherence to a healthy lifestyle; that blood glucose levels should be regularly tested; that the cardiovascular disease risk factors (such as smoking, hypertension and dyslipidemia) should be closely monitored; and that appropriate intervention measures should be provided. The specific objectives are (1) the BMI of overweight or obese patients should be lowered to approximately 24 kg/m2 or weight loss of at least 5–10% should be achieved, (2) the patients' total daily caloric intake should be reduced by at least 400–500 kcal (1 kcal = 4.184 kJ), (3) the patients' saturated fatty acid intake should be less than 30% of their total fatty acid intake and (4) the patients should be encouraged to engage in moderate-intensity physical activity for at least 150 min/week. Drug intervention trials in a pre-diabetic population showed that the oral administration of hypoglycaemic agents, such as metformin, α-glucosidase inhibitors, thiazolidinediones (TZDs), metformin combined with TZDs, the diet pill orlistat and traditional Chinese herbal medicine (Tianqi capsules), reduced the risk of diabetes 13, 17-21. However, because there is no sufficient evidence showing that drug interventions have long-term efficacy and/or health economics benefits, the clinical guidelines developed by various countries have not widely recommended medical interventions as the primary prevention for diabetes. Given that economic development in China is still in the preliminary stage and significant regional imbalances exist and that diabetes prevention-related health care is currently unsophisticated and imperfect, this guideline currently does not recommend the use of drug interventions to prevent diabetes. The clinical trials on intensive glucose control, such as the Diabetes Control and Complications Trial (DCCT) 22, the United Kingdom Prospective Diabetes Study (UKPDS) 23 and the Kumamoto Study in Japan 24, found that among patients in the early stage of diabetes, intensive glucose control can significantly reduce the risk of diabetic The study also showed that in obese or overweight the use of metformin was with a significant in the risk of and The long-term follow-up studies of the and populations indicated that early intensive control was with a in diabetic and a significant in the of and results evidence that intensive blood glucose control during the early of T2DM can reduce the of diabetic and This guideline recommends that for diagnosed diabetes patients and early T2DM strict control should be to reduce the risk of diabetic complications. The study showed that in patients diagnosed with diabetes, intensive blood pressure control not only significantly reduced the risk of diabetic also the risk of analysis of a in a of therapy and other clinical trials of therapy also showed that intensive blood pressure control reduced the risk of cardiovascular in diabetic patients significant complications The analysis of diabetic patients the Diabetes Study and other clinical studies indicated that the use of to lower lipoprotein cholesterol could reduce the risk of cardiovascular in diabetic patients significant complications. 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Therefore, the prevention of diabetic the and control of cardiovascular disease risk factors (e.g. high blood hypertension and dyslipidemia) and appropriate At the incidence of cardiovascular risk factors is high among T2DM patients in China, and are with T2DM, only for blood and total cholesterol The use of also more screening and treatment of cardiovascular risk factors and an rate of therapy are The clinical for screening and the and for patients with T2DM are shown in 3. to an epidemiological analysis of metabolic syndrome in the current Chinese population, this guideline the of the metabolic syndrome based on the The diagnostic criteria are as follows: (1) waist ≥90 cm and women ≥85 (2) high blood fasting blood glucose mmol/L or glucose at 2 after glucose mmol/L and/or diabetes diagnosis and (3) high blood blood pressure mmHg and/or diagnosed and on (4) fasting mmol/L and (5) fasting with or more of the aforementioned are diagnosed with metabolic