Global and regional level
In 2019, 2501.2 thousand incidence cases of CKD-T2D were reported globally, with an age-standardized incidence rate of 30.3 per 100,000, a 21.8% increase since 1990. The number of deaths due to CKD-T2D was 406.0 thousand, with an age-standardized death rate of 5.2 per 100,000, an increase of 24.6% since 1990. The number of DALYs for CKD-T2D globally was 9870.4 thousand, with an age-standardized rate of 120.2 per 100,000, an 18.2% increase since 1990 (Fig. 1 and Supplementary Table S1).
The trends in crude and age-standardized incidence, death, and DALY rates of CKD-T2D in the population aged 20–59 years in different regions globally between 1990 and 2019 were illustrated in Supplementary Fig. S1. The global age-standardized incidence rate exhibited an increasing trend, with the highest incidence rate observed in middle SDI countries. The global age-standardized death rate and DALY rate showed a slight increase, with the highest death and DALY rates observed in low-middle SDI countries.
Furthermore, we performed trend analysis using the Joinpoint software. Over the past 30 years, the global age-standardized incidence rate of CKD-T2D in the population aged 20–59 years showed an upward trend (AAPC = 0.7%, P༜0.05), with high SDI countries exhibiting greater fluctuations, a significant decline during 2005–2010 (APC=-1.3%, P༜0.05), followed by a significant increase since 2010 (APC = 1.4%, P༜0.05) (Fig. 2a). The global age-standardized death rate increased slightly (AAPC = 0.2%, P༜0.05), with varying degrees of decline observed in different SDI countries since 2016, and the most significant decrease in high SDI countries (APC=-1.6%, P༜0.05) (Fig. 2b). The global age-standardized DALY rate was similar to the death rate (AAPC = 0.3%, P༜0.05), with a downward trend observed in all five SDI countries since 2017, and the most significant decrease observed in high-middle SDI countries (APC=-2.8%, P༜0.05) (Fig. 2c).
National level
In 2019, the age-standardized incidence rate of CKD-T2D in the population aged 20–59 years in 204 countries globally ranged from 5.0 per 100,000 to 49.2 per 100,000, with the highest incidence rate observed in Costa Rica and the lowest in Uganda (Fig. 3a). The age-standardized death rate ranged from 0.1 per 100,000 to 14.2 per 100,000, with the highest in Mauritius (Fig. 3b). The age-standardized DALY rate ranged from 7.1 per 100,000 to 591.8 per 100,000, with the highest in Mauritius and the lowest in Iceland (Fig. 3c).
From 1990 to 2019, the percentage change in the age-standardized incidence rate of CKD-T2D in the population aged 20–59 years demonstrated significant variation across countries, with Bahrain experiencing the largest increase of 133.2%, whereas India (-4.4%) and Spain (-3.1%) exhibited contrasting trends (Supplementary Fig. S2a). During the same period, the largest increase in age-standardized death rate occurred in Armenia (388.2%), and the largest decrease was in Maldives (-64.4%) (Supplementary Fig. S2b). El Salvador (240.7%), Armenia (238.1%), and Mexico (178.2%) were the top three countries with the greatest increase in age-standardized DALY rate, while Maldives (-59.1%), Ethiopia (-57.9%), and Poland (-47.7%) exhibited the most substantial decreases (Supplementary Fig. S2c).
Age and sex patterns
The global incidence and death rates of CKD-T2D increased with age, peaking in the 75–79 age group and declining subsequently (Supplementary Fig. S3a), with the highest death rate in the oldest age group (≥ 95 years) (Supplementary Fig. S3b). For the population aged 20–59 years, the number and rate of incidence, death, and DALY all increased with age (Supplementary Fig. S4 and Table S2). While both sexes displayed comparable trends over the past 30 years (Supplementary Fig. S1), males bore a higher burden, with the number of deaths (Supplementary Fig. S4b) and DALYs (Supplementary Fig. S4c) for males roughly 1.3 times that of females in the 55–59 age group.
The effects of age, period, and cohort on the risk of CKD-T2D incidence, death, and DALYs were further explored (Fig. 4, Supplementary Table S3, and Fig. S5). Our findings demonstrated a persistent increase in the risk of CKD-T2D incidence, death, and DALYs with age, even after controlling for period and cohort effects. Specifically, in the 55–59 age group, the RR values for incidence, death, and DALYs were 8.21 (95% CI: 8.19–8.24), 7.02 (95% CI: 6.98–7.07), and 4.93 (95% CI: 4.92–4.93), respectively (Fig. 4, Supplementary Table S3, and Fig. S5). The period effects for incidence, death, and DALYs showed a slightly increasing trend from 1990 to 2015 (Fig. 4, Supplementary Table S3, and Fig. S5), with the incidence risk increasing from 2005 (RR = 1.06, 95% CI: 1.06, 1.06) to 2015 (RR = 1.46, 95% CI: 1.46, 1.47), and the risk of death increasing from 2005 (RR = 1.04, 95% CI: 1.04, 1.05) to 2015 (RR = 1.24, 95% CI: 1.23, 1.25), while the risk of DALYs was similar to the death during this period. The cohort effects indicated that the later-born cohorts had a lower risk of CKD-T2D incidence, death, and DALYs (Fig. 4, Supplementary Table S3, and Fig. S5).
Drivers of CKD-T2D epidemiology: population growth, aging, and epidemiologic changes
To explore the effects of population growth, aging, and epidemiological changes on the epidemiology of CKD-T2D in the population aged 20–59 years, we performed a decomposition analysis of raw DALYs. Overall, over the past 30 years, CKD-T2D DALY in the 20–59 age group has increased significantly globally, with the most pronounced increase in middle SDI countries (Fig. 5). Population growth and aging were found to be the primary contributors to the CKD-T2D DALY burden globally, accounting for 65.9% and 25.8%, respectively (Supplementary Fig. S6, Table S4). In middle SDI (65.2%), low-middle SDI (75.7%), low SDI (107.5%), and high-middle SDI (82%) countries, population growth was the key driver of the increase in CKD-T2D DALY, whereas, in high SDI countries, the contributions of population growth, aging, and epidemiological changes to DALY increase were relatively consistent. The epidemiological changes, which reflect the underlying changes in age and population-adjusted CKD-T2D incidence and death rates over the past 30 years, have declined in high-middle SDI, middle SDI, and low SDI countries while aging has only declined in low SDI countries (Fig. 5, Supplementary Fig. S6, Table S4).
Attributable risk factors for DALY in CKD-T2D
The GBD2019 study attributed CKD-T2D DALY to six risk factors across three primary categories, as outlined in Supplementary Table S5. Overall, globally, the DALY for CKD-T2D in the population aged 20–59 years showed a decreasing trend attributed to diet high in sodium, low temperature, and lead exposure over the past 30 years, while attributed to high systolic blood pressure, high body-mass index (BMI), and high temperature showed an increasing trend. The contribution of these risk factors to the overall burden of CKD-T2D DALY varied slightly across different SDI countries (Supplementary Fig. S7). In 2019, the top two attributable risk factors for CKD-T2D DALY globally in the population aged 20–59 years were high systolic blood pressure (37.2%) and high BMI (34.7%). Notably, CKD-T2D DALY in high SDI countries was more attributed to high BMI, whereas in low SDI countries were more attributed to high systolic blood pressure. Gender differences in the contribution of different risk factors were insignificant across different SDI countries (Fig. 6, Supplementary Fig. S8).
The Person correlation analysis was conducted to examine the relationship between the DALY for CKD-T2D attributable risk factors and SDI in the population aged 20–59 years. The results showed that the PAF of DALY due to high BMI was positively associated with SDI (R = 0.62 to 0.65, P < 0.001), high temperature (R = -0.35 to -0.38, P < 0.001), and lead exposure (R = -0.62 to -0.64, P < 0.001) were negatively associated with SDI. Moreover, diet high in sodium showed a positive correlation with SDI in 30–49 years old (R = 0.15 to 0.19, P < 0.05), while low temperature was positively correlated with SDI in 45–59 years old (R = 0.17 to 0.27, P < 0.05). In contrast, no correlation was observed between high systolic blood pressure and SDI (R = 0.02 to 0.12, P > 0.05) (Supplementary Fig. S9).