Background: Obesity has largely been associated with type 2 diabetes, while people with type 1 diabetes (T1DM) are usually lean at diagnosis. Given the growing prevalence of obesity in the general population, people with T1DM are at increased risk of weight gain, insulin resistance and developing double diabetes (DD). People with DD are at increased risk of micro/macrovascular complications and mortality. In this study we aimed to examine the prevalence and impact of overweight/obesity in people with T1DM.
Methods: We conducted a retrospective cross-sectional study of consecutive patients with T1DM who attended an adult diabetes clinic between January and September 2019 in a secondary care hospital. Data was collected from electronic patients records. Estimated glucose disposal rate (eGDR) was utilised as marker of insulin resistance and an eGDR value of <8 used to identify individuals with DD. Data is presented as mean ± standard deviation, or numbers (percentage).
Results: The records of 103 people with T1DM were screened with 10 excluded as no body mass index (BMI) data was available. Study population had mean age of 48.1 (±17.1) years; BMI 27.5 (±6.1) kg/m2, and 46 (49.5%) were females. The prevalence of overweight/obesity was 56/93 (60.2%), and of obesity 30/93 (32.6%). People with T1DM and overweight/obesity compared to those with normal BMI had longer duration of diabetes (21.3 vs 12.7 years, P=0.004); higher total daily insulin dose (72.2 vs 39.5 units, P<0.001), and higher DD prevalence (76.8% vs. 27.0%, P<0.001); but similar HbA1c (67.8 vs. 70.6 mmol/mol, P=0.35). There was an association between increasing BMI and decreasing eGDR, R2=0.503. People with T1DM and overweight/obesity had an odds ratio of 42.6 to suffer from DD compared to those with normal BMI (95% confidence interval 4.9369.0, P<0.001).
Conclusions: Overweight/obesity is common in people with T1DM and requires more attention. People with T1DM and overweight/obesity are at increased risk of DD and subsequent risk of complications. Longer duration of T1DM is associated with higher BMI independent of age or glycaemic control. Interventions aiming to prevent weight gain early on after the diagnosis with T1DM are needed.