BMI and waist circumference are associated with impaired glucose metabolism and type 2 diabetes in normal weight Chinese adults.

To examine the associations of BMI and waist circumference with glucose metabolism and (pre)diabetes among adults with BMI < 25 kg/m2. We conducted a cross-sectional study in a nationally representative sample (10,098 men and 17,454 women) of Chinese adults aged ≥20 years with BMI < 25 kg/m2. Glucose levels after at least 10 hours of overnight fasting, at 30 minutes and at 120 minutes after a standard 75-g oral glucose load were measured. Associations of BMI and waist circumference with outcomes were examined by general linear models for continuous outcomes and by logistic regression models for dichotomous outcomes. Among those with BMI < 25 kg/m2, 18.8% of men and 17.1% of women had abnormal glucose metabolism, including 4.9% of men and 3.8% of women with undiagnosed type 2 diabetes. For each SD increase in BMI (2.1 kg/m2) and waist circumference (8.3 cm), fasting glucose levels increased by 0.128 and 0.170 mmol/L in men, and by 0.112 and 0.167 mmol/L in women, respectively; the corresponding increases for 2-hour post-load glucose levels were 0.121 and 0.217 mmol/L in men, and 0.241 and 0.362 mmol/L in women. When simultaneously included in the same model, these associations with waist circumference were stronger than with BMI. Obesity measures are associated with abnormal glucose metabolism and diabetes, with central obesity playing a more prominent role than general obesity in Chinese population with BMI < 25 kg/m2. Chinese diabetes prevention and treatment programs should incorporate targeting of normal weight adults with central obesity.

在体重指数（BMI）<25 kg/m²的成年人中研究BMI和腰围与糖代谢以及（前期）糖尿病的关联。 我们在中国年龄≥20岁且BMI<25 kg/m²的具有全国代表性的样本（10098名男性和17454名女性）中进行了一项横断面研究。测量了至少禁食10小时后的血糖水平，以及在标准75克口服葡萄糖负荷后30分钟和120分钟的血糖水平。通过一般线性模型分析连续型结局，通过逻辑回归模型分析二分类结局，以研究BMI和腰围与结局的关联。 在BMI<25 kg/m²的人群中，18.8%的男性和17.1%的女性存在糖代谢异常，其中包括4.9%的男性和3.8%的女性患有未确诊的2型糖尿病。BMI每增加一个标准差（2.1 kg/m²）以及腰围每增加一个标准差（8.3 cm），男性的空腹血糖水平分别升高0.128 mmol/L和0.170 mmol/L，女性分别升高0.112 mmol/L和0.167 mmol/L；男性负荷后2小时血糖水平相应升高0.121 mmol/L和0.217 mmol/L，女性分别升高0.241 mmol/L和0.362 mmol/L。当同时纳入同一模型时，腰围与这些指标的关联比BMI更强。 肥胖指标与糖代谢异常和糖尿病相关，在中国BMI<25 kg/m²的人群中，中心性肥胖比全身性肥胖所起的作用更显著。中国的糖尿病防治项目应将中心性肥胖的正常体重成年人纳入防治目标。