Geographic, Gender, and Seasonal Variation of Diabetes: A Nationwide Study With 1.4 Million Participants

Context: China has experienced a rapid increase in the prevalence of diabetes. Objective: We assessed the prevalence of diabetes among Chinese adults who attended preventive physical examinations and analyzed geographical and gender difference in seasonal variation of fasting blood glucose (FBG). Methods: The study used data from 1 390 088 participants attending preventive health examination at 430 health screening centers in 220 cities. Diagnosis of diabetes and prediabetes were based on FBG and glycated hemoglobin A1c and self-reported physician's diagnosis. We calculated age- and sex-standardized prevalence of diabetes according to the sixth Chinese population census data in 2010. Geographical distribution of diabetes and prediabetes were represented on a country map. FBG levels were analyzed to detect seasonal variation adjusted for age and gender by geographic location. Results: The standardized prevalence of diabetes was 8.70% (95% CI, 8.22%-9.19%), 10.7% in men and 6.61% in women. Among those with diabetes, 43.7% (95% CI, 40.9%-46.5%) were aware of their conditions and 38.5% (95% CI, 36.0%-41.1%) were treated. Only 49.3% (95% CI, 47.0%-51.6%) of treated patients achieved glycemic control. The mean level of FBG was higher in winter than summer and in the northern than the southern region. Conclusion: The prevalence of diabetes was high while the percentages of awareness, treatment, and glycemic control were low among adults. Effective measures are needed to prevent and manage diabetes in China. Geographic and seasonal variation of diabetes should be considered for its prevention and control.