The younger the age at which type 2 diabetes is diagnosed, the greater the risk of death.

Discover why early detection of diabetes can be a lifesaver: new study reveals alarming mortality trends in younger patients

study: Age at Diagnosis of Type 2 Diabetes and Mortality Risk in the U.S. Population. Image credit: Eviart / Shutterstock

In a recent study published in the journal scientific reportResearchers investigated the relationship between age at diagnosis of type 2 diabetes (T2D) and mortality.

T2D is a common public health concern characterized by hyperglycemia due to β-cell destruction and insulin resistance. In 2021, 537 million people were affected by T2D, and it is predicted to reach 783 million by 2045.

Although T2D has historically been observed in middle-aged and older populations, it is increasingly prevalent in younger age groups. Early-onset T2D is more progressive, has a higher relative risk of diabetes-related complications and mortality, and has poorer outcomes.

About research

In this study, researchers evaluated the relationship between age at T2D diagnosis and cardiovascular disease (CVD) and all-cause mortality. The research team used data from the National Health and Nutrition Examination Survey (NHANES), which is representative of the United States (US) population and was conducted from 1999 to 2018 on more than 101,000 people.

Diabetes was defined as: 1) self-reported medical history, 2) taking diabetes medications to lower blood sugar, 3) glycated hemoglobin (HbA1c) ≥ 6.5%, and 4) fasting plasma glucose level ≥ 126 mg/dL. Defined. Age at T2D diagnosis was self-reported and stratified into three categories: <40 years, 40–59 years, and ≥60 years. A standardized household questionnaire was administered to collect sociodemographic information.

Linear regression models and chi-square tests compared continuous and categorical variables. Multivariate Cox regression models were used to examine the association between age at T2D diagnosis and (all-cause and cardiovascular) mortality. One model was adjusted for age, sex, and race. The other was further adjusted for marital status and education. The third model was further adjusted for alcohol intake, smoking status, body mass index (BMI), estimated glomerular filtration rate (eGFR), hyperuricemia, hypertension, CVD, and diabetes duration.

In addition, standardized mortality rates were calculated using propensity score matching. Each diagnostic age group was matched 1:1 with a corresponding nondiabetic group based on age, gender, and race.

Restricted cubic spline regression analyzes assessed potential exposure-effect relationships between mortality and age at T2D diagnosis.

Additionally, subgroup analyzes investigated potential modifications of associations across several variables. To ensure the robustness of our results, we conducted a sensitivity analysis in subjects with previously diagnosed diabetes.

Survey results

The study involved 8,654 participants with an average age of 59.61 years. The mean age at T2D diagnosis was 51.7 years. Most participants were male (51.59%) and non-Hispanic White (35.19%). Three age groups (<40 years, 40–59 years, and 60 years and above) were followed for 67,554, 67,609, and 67,625 person-years, respectively. The median age at T2D diagnosis was 44.04, 57.5, and 72.2 years, respectively.

Participants diagnosed at a younger age were more likely to be current smokers, female, Mexican American, non-Hispanic black, had higher rates of insulin use, and had diabetes for longer. These subjects had lower education and income levels and higher HbA1c, BMI, eGFR, and fasting plasma glucose levels. Of note, participants diagnosed at a younger age had a lower prevalence of comorbidities (CVD, hyperuricemia, or hypertension).

Overall, 722 deaths were recorded from cardiovascular disease and 2,582 from all causes. In unadjusted models, older age at T2D diagnosis was associated with higher all-cause and cardiovascular mortality. Nevertheless, after adjustment, older age at diagnosis was associated with lower cardiovascular and all-cause mortality. This meant that the risk of death increased as the age at diagnosis decreased. For example, the hazard ratio (HR) for all-cause mortality in the <40 years group compared to the >60 years group was 2.72 (95% CI: 1.83-4.05) after full adjustment.

In sensitivity analyses, younger age at T2D diagnosis was associated with higher cardiovascular and all-cause mortality. Restricted cubic spline regression analysis revealed a linear relationship between age at diagnosis and all-cause mortality.

Interestingly, this analysis also revealed that there is a tipping point for cardiovascular disease mortality at age 54, with risk decreasing until age 54 and gradually increasing thereafter.

Subgroup analyzes found no significant interactions based on gender, race, eGFR, BMI, CVD, and alcohol intake. However, the association between age at diagnosis and mortality was significantly stronger for people with hypertension and current smokers.

conclusion

Taken together, these results indicate that younger age at T2D diagnosis is associated with higher risk of both cardiovascular and all-cause death. This association was significantly stronger among current smokers and those with high blood pressure.

The results of this study highlight the importance of early diagnosis and intervention strategies for T2D, especially in young people. The results also highlight the need for individualized risk prediction and management, especially for people with hypertension and current smokers.

Limitations of this study include reliance on questionnaire data, which is subject to recall bias, lack of recording of diabetes type in NHANES, and limited generalizability due to the US-based sample.