Progress of cardiovascular risk factors in relation to age at diagnosis of type 2 diabetes: An observational study of 100,606 patients from the Swedish National Diabetes Register

Background: In the past few decades, the incidence and prevalence of type 2 diabetes mellitus (T2DM) has increased dramatically and age of disease onset has declined. This is mainly explained by the obesity epidemic. Cardiovascular disease is the most common cause of mortality in patients with T2DM and from a cardiovascular perspective, there is evidence suggesting that early-onset T2DM is a more aggressive disease than usual-onset T2DM. Persons with early-onset T2DM have been reported as being more obese, having poorer glycemic control and display a more pronounced dyslipidemia than those with usual-onset T2DM. Aim of this study: The aim of this study was to evaluate, in relation to age at diagnosis: 1) clinical characteristics at diagnosis and 2) trajectories in CVD risk factors over several years in patients with T2DM. Patients and methods: Data was obtained from the Swedish National Diabetes Register (NDR), where we identified patients who were defined epidemiologically as T2DM and had a listing in the NDR between 2002 and 2012. We included patients who were examined at the year of diagnosis. We restricted follow-up time to a maximum of 10 years. Our final cohort consisted of 100,606 patients contributing 679,420 observations. Continuous outcome variables were analysed using a mixed effect model for repeated measures. Dichotomous outcome variables were analysed using a corresponding mixed generalized linear model with a logistic link function. Results: HbA1c levels at diagnosis were highest in patients diagnosed under the age of 50 years and decreased gradually with increasing age at diagnosis. Patients with early-onset T2DM also displayed the worst progress in glycemic control. The youngest patients had the highest BMI at diagnosis; nearly 70% of them were obese. All age groups displayed a reduction in BMI during follow-up, and the youngest patients displayed the most pronounced decrease. Systolic blood pressure decreased during follow-up in patients diagnosed at 50 years of age or older, but remained unchanged in patients diagnosed under the age of 50 years. HDL cholesterol and triglycerides displayed similar trends. In both cases younger patients had poorer characteristics at diagnosis. Considering HDL, patients in the age range of 18 to 79 displayed an increase during follow-up, but the oldest age group remained unchanged. Furthermore, triglyceride levels decreased slightly during follow-up, with the youngest age group displaying the steepest decline. eGFR levels were highest in the youngest patients and rapidly decreased as patients were diagnosed in older ages. Patients in the oldest age group had the highest prevalence of microalbuminuria at diagnosis. The odds of having microalbuminuria increased in all age groups with increasing duration of diabetes, with no obvious differences in relation to age. Conclusion: Patients with early-onset T2DM have a more adverse cardiovascular risk profile at diagnosis and poorer progression of glycemic control, compared to patients diagnosed at an older age. These individuals, because of their young age, will have very high lifetime risk of developing CVD. This means that we should pay more attention to this patient group. We argue that screening for diabetes in young obese patients should be performed generously and evidence based interventions should be implemented promptly.