Analysis of blood glucose distribution characteristics in a health examination population in Chengdu (2007-2015).

With socioeconomic growth and cultural changes in China, the level of blood glucose may have changed in recent years. This study aims to detect the blood glucose distribution characteristics with a large size of health examination population.A total of 641,311 cases (360,259 males and 281,052 females) more than 18 years old during 2007 to 2015 were recruited from the Health Examination Center at West China hospital, Sichuan University.The percentage of cases with abnormal glucose level and the mean level of glucose were significantly increased since 2007 to 2015 overall. The percentage of cases with abnormal glucose level in males was significantly higher than that in females every year, and the percentage of cases with abnormal glucose level in aged population was higher than the young population. In addition, the mean level of glucose was higher in aged population with normal level of glucose than the young population with normal level of glucose, and the mean level of glucose was higher in males with normal level of glucose than the females with normal level of glucose.The population showed an increased level of blood glucose. Some preventive action may be adopted early and more attention can be paid to them.

Introduction

Diabetes mellitus (DM) prevalence and incidence are growing steadily for several decades, leading to large increases in the total burden of diabetes-related morbidity. The annual cost of diabetes has been estimated to be $245 billion in the United States[ and $548 billion worldwide.[ In the 1980s, the Chinese Government initiated a series of political and economic reforms that have led to phenomenal socioeconomic growth, technological advancement, and cultural changes. These rapid changes in lifestyle may have contributed to the dramatic increase in diabetes prevalence from 0.9% in 1980[ to 11.6% in 2010.[ A Chinese national survey in 2010 showed that the prevalence of type 2 diabetes was 4.5% in person aged 18 to 29 years and 6.6% in those aged 30 to 39 years. With respect to the person under the age of 40 years, about 40% to 50% had prediabetes.[ Type 2 diabetes has overtaken type 1 diabetes as the predominant form of diabetes in children in Taiwan and Hong Kong,[ similar to that in the western countries.[ Together with the prevalence of gestational diabetes of 8.1% to 10.9%[ and childhood obesity of 5.5%,[ early onset type 2 diabetes substantially up-regulates the risk of premature mortality and multiple morbidities partly due to long disease duration[ suboptimal management,[ and has become into a major public health challenge.[ Therefore, early detection, diagnosis, and treatment are of importance for the prevention and control of DM.

Regular health examination is an important way for early detection of DM and glucose intolerance. In the present study, we analyzed the fasting blood glucose from 2007 to 2015 in West China Hospital, Chengdu, so as to reveal the blood glucose distribution characteristics among the health examination population.

Methods

Study population

The following methods were carried out in accordance with the approved guidelines. A total of 641,311 cases more than 18 years old during 2017 to 2015, included 360,259 males (45.03 ± 13.96 years) and 281,052 females (42.52 ± 13.64 years) were recruited from the Health Examination Center at West China Hospital, Sichuan University. Peripheral blood was collected from all participants. The corresponding protocol was approved by the Ethics of Research Committee of the West China Hospital, Sichuan University. Informed and written consent was obtained from all participating subjects.

Collection of laboratory data and glucose measurement

Data about demographic and laboratory features were collected from hospital records or by questionnaire. The blood samples were withdrawn from the antecubital vein of subjects in fasting status, and the level of fasting blood glucose of each individual was detected by hexokinase method by Roche cobase 702. Cases having serum level of fasting blood glucose between 2.2 and 6.1 mmol/L were considered as normality, while serum level of fasting blood glucose <2.2 or >6.1 mmol/L were considered as abnormality.[ In addition, the level of glycosylated hemoglobin a1c (HbA1c) was detected by high performance liquid chromatography (HLC-723G7; Tosoh, Tokyo, Japan), which was certified by the National Glycohemoglobin Standardization Program.[ The level of HbA1c higher than 6.5% was considered abnormality.[

Statistical analysis

All statistical analyses were done by SPSS 10.01. With respect to the results expressed as mean ± standard deviation, the statistical significance of the data was determined by Student t test, analysis of variance analysis, or multiple comparisons (SNK-q test). The difference between percentages of males and females having normal glucose level was compared using Chi-squared test. To describe the level of fasting blood glucose, we noted the maximum, minimum, mean, and standard deviation. Significance was defined as P < .05.

Results

Characteristics of the health examination population and the fasting blood glucose

In the present study, a total of 641,311 cases over than 18 years old including 360,259 males (45.03 ± 13.96 years) and 281,052 females (42.52 ± 13.64 years) were recruited (Table 1). Among these population, we found that the mean level of glucose in year 2007 was 4.81 mmol/L, and the mean level was significantly increased from 2007 to 2015 (F = 897.23, P < .001), by which the level was 5.33 mmol/L in year 2015. When discussed the glucose level between year 2008 and 2007, there was significant difference. Similarly, the other 7 year's glucose level was significantly higher than that in 2007, respectively (Table 2).

Table 1

Characteristics of all the health examination population and the cases with normal level of fasting blood glucose.

Table 2

Characteristics of fasting blood glucose among all the health examination population (2007–2015).

In year 2015, there were 45,575 participants examining the level of HbA1c. We found that 27,109 were males and 18,466 were females, and the percentage of cases had normal level of HbA1c was 85.98% in males and 92.33% in females (Table 3). Among all the cases, the minimum level of HbA1c was 2.9%, the maximum level of HbA1c was 15.9%, and the mean level of HbA1c was 5.45 ± 0.31%.

Table 3

Characteristics of all the health examination population and the cases with normal level of glycosylated hemoglobin a1c (HbA1c) in year 2015.

Differences between males and females having normal glucose level

There were 317,638 males (88.17%) and 265,204 females (94.36%) showing with normal level of glucose (Table 1), and the percentage of males having normal glucose level was significantly lower than that in the females overall (χ2 = 7305.2, P < .001). With respect to different years (2007–2015), the percentage of males having normal glucose level was also significantly lower than that in the females every year, respectively (all P < .01, data not shown). To further discuss the level of glucose in different sex, we examined the level of glucose both in males and females every year. Results showed that the mean level was significantly increased from 2007 to 2015 both in males and females (Table 4). These data indicated that the mean level of glucose was higher in males compared with that in females every year.

Table 4

Characteristics of the cases with normal level of glucose in different sex.

Regarding the level of glucose among different ages, we divided the ages into 8 groups. As in Table 5 , the mean level of glucose increased from 4.39 mmol/L in year 2007 to 4.77 mmol/L in year 2015 in group 1. The mean level of glucose was significantly increased from 2008 to 2015 when compared with 2007, respectively. The results of other 7 groups were similar to group 1. These data suggested that the level of glucose was gradually increased year by year in each group, and the level of glucose was higher in aged cases compared with the young population every year overall, for instance, the mean level of glucose was 4.39 mmol/L in group 1, and the mean level was 4.90 mmol/L in group 8 in year 2007. To discuss the difference of cases having normal HbA1c level among different ages, we also divided the ages into 8 groups in year 2015. Results indicated that the mean level of HbA1c was 5.15 ± 0.28% in group 1, and the mean level was gradually increased from group 2 to group 8 when compared with group 1 (Table 6).

Table 5

Characteristics of the cases with normal level of glucose in different ages.

Table 5 (Continued)

Characteristics of the cases with normal level of glucose in different ages.

Differences between males and females with abnormal glucose level

There were 42,621 males (11.83%) and 15,848 females (5.64%) showing with abnormal serum level of glucose. With respect to the glucose level <2.2 mmol/L, there were 1 male and 1 female in year 2008, 1 female in year 2011, 2 males and 1 female in year 2012, and 1 male in year 2014. According to the cases with higher level of glucose than 6.1 mmol/L, we found that the percentage was 6.12% among males, while the percentage was 2.76% among females in year 2007. However, the percentage was gradually increased and up-regulated to 12.88% among males, 5.89% among females in year 2015 (Fig. 1). In addition, the percentage was significantly higher in males compared with that in females every year, respectively (all P < .001). To discuss the percentage of abnormal glucose level among different ages, we also divided the ages into 8 groups. As in Fig. 2, the difference of percentage of abnormal glucose level in each year among different groups was significant, respectively (all P < .001). For instance, groups 1 and 2 were lower than the other groups every year, and the percentage of abnormal glucose level in groups 3 to 8 was gradually increased year by year overall. Similarly, the percentage of cases having level of HbA1c higher than 6.5% was 13.51% in male, and 7.05% in female in year 2015. To discuss the percentage of abnormal HbA1c level among different ages, we also divided the ages into 8 groups in year 2015. Results indicated that the percentage of cases having abnormal HbA1c level was comparable between group 1 (1.75%) and group 2 (0.68%). However, the percentage was significantly increased from group 3 to group 8 when compared with the percentage in group 1, respectively (all P < .05, data not shown).

Figure 1

Trends of the percentage of cases with fasting blood glucose more than 6.2 mmol/L in different sex. Percentages of male and female with fasting blood glucose more than 6.2 mmol/L were both gradually increased since 2007 to 2015 overall. The percentage of male with fasting blood glucose more than 6.2 mmol/L was higher than that in female every year (∗∗P < .001).

Figure 2

Trends of the percentage of cases with fasting blood glucose more than 6.2 mmol/L in different ages. The percentage of cases with fasting blood glucose more than 6.2 mmol/L in group 1 (18–20 year) and group 2 (21–30 year) was comparable every year. The percentage of cases with fasting blood glucose more than 6.2 mmol/L was gradually increased in groups 3 to 8 from 2007 to 2015 overall. Cases with older age showed significantly higher percentages than that in younger age every year (∗∗P < .001).

Discussion

The present study was conducted in 641,311 persons with health examination higher than 18 years old from Chengdu City in Sichuan province and the surrounding areas during 2007 to 2015. This was a large sample size study, with subjects from the same area, supporting the accuracy and stability of the results. This investigation discussed the serum level of fasting blood glucose both in males and females year by year, and found that the percentage of cases with abnormal glucose level and the mean level of glucose were increased since 2007 to 2015 overall. This study also revealed that the percentage of abnormal glucose level in males was higher than that in females every year. It is noteworthy that the percentage of cases with abnormal glucose level in aged populations was higher than the young population, and the mean level of glucose was higher in the aged population with normal level of glucose than the young population with normal level of glucose. These findings are interesting, and suggested that the mean level of glucose was gradually up-regulated since 2007 to 2015, and the males may have higher serum levels of glucose than females.

The findings in this study may correlate with several reasons. First, oxidative phosphorylation dysfunction of islet cells, with a down-regulation in the amount and secretory functions, results in glucose elevation with age,[ similar to a study in Song et al,[ who indicated a strong increasing tendency of glucose with age, and the prevalence of impaired fasting glucose was positively correlated with age, where the glucose of males reached a peak at the age of 65, while it always continued increasing in females. This was partly similar to our study, by which the level of glucose was higher in aged population and reached a peak at group 7 (71–80 years). In addition, some studies found a higher incidence of DM in men than women.[ Habits such as alcohol consumption, smoking, increased age, and physical activity levels may result in the up-regulation of DM in males.[ Moreover, it has been accepted that life and job stress are much higher in males than in females in China, less attention has been paid to them, and an unhealthy lifestyle might also result in a rise in blood glucose. Because of the specificity and acceptability in health examination population, the present study failed to analyze the causality relationship between blood glucose and related factors. Second, increased level of glucose may correlate with socioeconomic growth, the rapid adoption of energy-dense foods. Importantly, these significant changes may lead to serious diabetes or prediabetes. In a national study discussing the prevalence of diabetes and glycemic control in the Chinese adult population, the estimated prevalence of diabetes among a representative sample of Chinese adults was 11.6% and the prevalence of prediabetes was 50.1%, suggesting that this may represent up to 113.9 million Chinese adults with diabetes and 493.4 million with prediabetes. In our study, the proportion of population with abnormal level of glucose and the mean level of glucose were increased year by year overall. Therefore, preventive interventions for cases with high level of glucose or aged cases should be used as early as possible. The Da Qing Diabetes Prevention Program was the first randomized study conducted in China that has revealed significant benefits of lifestyle modification on down-regulating the risk of progression from impaired glucose tolerance (IGT) to diabetes.[ This program showed that after 6 years of active intervention, the risk of progression to diabetes was down-regulated by 51% in comparison with the control group irrespective of obesity status at baseline. This benefit persisted after 20 years with an annual incidence of diabetes of 7% in the intervention group compared with 11% in the control group. Moreover, in the Finnish Diabetes Prevention Study, a total of 522 middle-aged, overweight subjects with IGT were randomized to receive personalized counseling for promoting healthy lifestyle. After a mean follow-up duration of 3.2 years, the risk to develop diabetes was down-regulated by 58% in the intervention group.[ Furthermore, a study of the Diabetes Prevention Program involving 3234 American adults with impaired fasting glycemia or IGT reported that the incidence of diabetes was down-regulated by 58% with lifestyle intervention and 31% with metformin after 2.8 years of intervention, in comparison with the control group.[ Collectively, these encouraging results have provided support for us though the present study did not discussed the prevalence of diabetes or prediabetes, the current findings have revealed that the percentage of cases with abnormal glucose level has increased year by year, and the mean level of glucose has up-regulated since 2007 to 2015. Consequently, we should pay attention to this health examination population, and some preventive action may be adopted early.

There are several limitations in the present study, such as representativeness, missing biochemical indexes, and missing information of diet and exercise. In addition, our study failed to explore the causality relationship between blood glucose and related factors because of inherent limitations of the cross-sectional study. Despite these limitations, this study was a large sample size investigation, with subjects from the same area, supporting the accuracy and stability of the results. Moreover, the results of this study are noteworthy for government for early education and intervention.

In summary, increased percentage of cases with abnormal glucose and mean level of glucose were observed in a large population of adults. It is necessary to take action for health examination population, especially aged population, and screen high-risk groups and adopt appropriate preventive measures early.

Table 6

Characteristics of the cases with normal level of glycosylated hemoglobin a1c (HbA1c) in different ages in year 2015.