Global burden of diabetes mellitus
The worldwide incidence of diabetes mellitus increased by 102.9%, from 11,303,084 in 1990 to 22,935,630 in 2017, and changes in ASR were prominent. The global ASR increased from 233.6 per 100,000py in 1990 to 284.6 per 100,000py in 2017 (EAPC = 0.87, 95% CI:0.79,0.96). The ASR of diabetes mellitus varied considerably across the world in 2017, being highest in Kiribati (970.1 per 100,000py), followed by Fiji and American Samoa (these countries are not marked on the map in the figure), and lowest in Colombia (186.9 per 100,000py), followed Japan and China (Fig.1A). As for the absolute number, the largest number of diabetics in 2017 were in India (>3.6 million), followed by China and the USA.
The number of diabetes mellitus cases increased in both sexes from 1990 to 2017. The incidence in males increased by 103.3%, from 5,790,650 in 1990 to 11,769,740 in 2017, while that in females increased by 102.6%, from 5,512,440 to 11,165,890. The ASR increased by annually an average of 0.89 (0.81,0.99) in males and 0.85 (0.77,0.94) in females (Table 1).
The numbers of diabetes mellitus (T1DM and T2DM) cases increased across the five SDI regions (Fig. 3). However, the increasing trend of ASR differed with disease types and regions. The increase in ASR was largest in high-SDI regions (EAPC = 1.05, 95% CI:0.92,1.17) and smallest in low-SDI regions (EAPC = 0.79, 95% CI:0.71,0.88) (Table 1). The numbers of diabetes mellitus (T1DM and T2DM) cases increased from 1990 to 2017 in the most geographical regions (Fig. 4), with the increase being largest in western Sub-Saharan Africa (203.6%), followed by North Africa and the Middle East (195.1%). The largest increase in ASR was found in high-income North America (EAPC = 1.98, 95% CI:1.64,2.31), while the largest decrease was found in tropical Latin America (EAPC = –0.30, 95% CI: –0.40, –0.19) (Table 1).
The incidence of diabetes mellitus increased the most in the United Arab Emirates (964.1%) and decreased the most in Bulgaria (–0.69%) (Fig. 1B). The EAPC in ASR was 0.87 (95% CI:0.79,0.96) worldwide, increasing from 233.58 per 100,000py in 1990 to 284.56 per 100,000py in 2017 (Table 1). The increase in ASR was largest in Mauritius (EAPC = 2.56, 95% CI:2.32,2.81), followed by Sri Lanka and the USA (Fig. 1C). There were 20 countries in which the ASR of diabetes mellitus decreased between 1990 and 2017 (Fig. 1C): Greenland, Ethiopia, Singapore, Colombia, New Zealand, Qatar, Canada, Brazil, Saint Lucia, Iraq, Cuba, Rwanda, Uruguay, Brunei, Tobago, Trinidad, Japan, Belarus, Kyrgyzstan, and Bermuda.
Type 1 diabetes
T1DM accounted for nearly 1.7% (n = 400,289) of the total number of diabetes mellitus cases in 2017, while the proportion exceeded 5% in Greenland. The rate was highest in Norway (19.7 per 100,000py), followed by Canada and Uruguay (Fig. S1A). The incidence of T1DM in 2017 was less than 16.7 per 100,000py in other countries. The incidence in the country with the highest rate (Norway) was 9.7 times higher than that in the country with the lowest rate (Vietnam, 2.0 per 100,000py). The absolute global number of T1DM cases increased by 37.8%, from 290,581 in 1990 to 400,289 in 2017 (Fig. S3A).
Examining the relationship between all age groups and incidence revealed that the incidence of T1DM increased from the 1-age group to the 5-age group, peaked in the 5-age group, and decreased to the lowest values in the 60-age group, after which it slightly increased in both sexes (Fig. 5A). The ASR of T1DM did not change in low-SDI regions (EAPC = 0.00, 95% CI: –0.03,0.02), while the largest increase was found in high-SDI regions (EAPC = 0.80, 95% CI:0.70,0.90) (Table S1). T1DM cases increased across four SDI regions from 1990 to 2017, and the number of patients with T1DM was the highest in the high-SDI region (Fig. 3A).
The global ASR of T1DM displayed an increasing trend from 1990 to 2017, with an EAPC of 0.34 (95%CI:0.30,0.39) (Table S1). As shown in Fig.4A, the number of T1DM cases increased in 18 geographical regions, with the increase being highest in western Sub-Saharan Africa (129.5%), followed by central Sub-Saharan Africa (123.2%). The number of T1DM cases decreased in three regions:high-income Asia-Pacific (–21.6%), central Europe (–2.1%), and East Asia (–0.2%). The largest increase in ASR was observed in high-income North America (EAPC = 1.20, 95% CI:1.04,1.36), followed by Australasia and central Europe (Fig. 2). The largest decrease in ASR was found in tropical Latin America (EAPC = –0.19, 95% CI: –0.49,0.11) (Table S1, Fig. 2). At the national level, the largest increase was observed in Qatar (493.5%) followed by the United Arab Emirates (382.0%) and Afghanistan (257.6%) (Fig. S1B). Meanwhile, the largest decrease was found in Georgia (–31.9%), followed by Bosnia and Herzegovina (26.6%) (Fig. S1B). The largest increase in ASR of T1DM was observed in France (EAPC = 2.11, 95% CI:1.93,2.29), followed by Ireland and Greece, and the largest decrease in ASR was found in Finland (EAPC = –0.72, 95% CI: –0.44,–1.00), followed by Ireland (Fig. S1C, Fig. 2).
T2DM accounted for 98.3% (22,535,341) of the total number of diabetes mellitus cases in 2017. The absolute number of T2DM cases globally increased by 104.6%, from 11,012,503 in 1990 to 22,535,341 in 2017 (Fig. S3B). In the 194 countries in 2017, 36% of the incident cases of T2DM occurred in India, China, and USA (about 8.2 million in total), while 10% of them occurred in Indonesia, Mexico, and Pakistan (about 2.3 million in total). The highest rate in 2017 was observed in Kiribati (967.6 per 100,000py), followed by Fiji and American Samoa. The incidence in the country with the highest rate (Kiribati) was 5.5 times higher than that in the country with the lowest rate (Japan, 176.9 per 100,000py).
Examining the relationship between all age groups and incidence showed that the incidence of T2DM increased from the 10-age group to the 55-age group, peaked in the 55-age group, after which it decreased slightly in both sexes (Fig. 5B). The increase was largest in high-SDI regions (EAPC = 1.06, 95% CI:0.93,1.19) while the decrease was largest in low-SDI regions (EAPC = 0.81, 95% CI:0.72,0.90) (Table S2). T2DM cases increased across all five SDI regions, and the number of patients with T2DM from 1990 to 2017 was highest among countries in the middle-SDI region (Fig. 3B).
The global ASR of T2DM showed an increasing trend from 1990 to 2017, with an EAPC of 0.89 (95% CI:0.80,0.97). As shown in Fig.4B, the number of T2DM cases increased in all 21 regions, with the highest increase observed in western Sub-Saharan Africa (207.4%), followed by North Africa and the Middle East (199.3%), and the smallest increase was found in Eastern Europe (14.3%). The increase in ASR was largest in high-income North America (EAPC = 2.07, 95% CI:1.72,2.42), followed by southern and western Sub-Saharan Africa (Table S2, Fig. 2). At the national level, the largest increase was observed in the United Arab Emirates (975.8%) and the largest decrease was found in Bulgaria (–0.4%) (Fig. S2B). The largest increase in ASR was in Mauritius (EAPC = 2.57, 95%CI:2.33,2.82), followed by the USA (EAPC = 2.38, 95% CI:1.97,2.78), and the largest decrease was in Greenland (EAPC = –1.41, 95% CI: –1.47, –1.35) (Fig. S2C).
As shown in Fig. 6, a significant association was detected between EAPC and the HDI in 2017. The HDI in 2017 can serve as a surrogate for the level and availability of health care in each country, and a significant negative correlation was detected between EAPC and HDI (ρ = –0.21, p = 0.006). As HDI increased, countries experienced a more-steady decrease in the ASR of diabetes mellitus from 1990 to 2017. In addition, the study found that the ASR of T1DM differed with latitude and the farther away from the equator, the higher the ASR in 2017 (ρ = 0.61, p<0.0001)Fig. S4).