Relationship between a single measurement at baseline of body mass index, glycated hemoglobin, and the risk of mortality and cardiovascular morbidity in type 2 diabetes mellitus

Objective: This study aims to evaluate the relationship between a single measurement at baseline of body mass index (BMI), glycated hemoglobin (HbA1c) and subsequent clinical outcomes in patients with type 2 diabetes mellitus (T2DM).

Method: Patients with T2DM were recruited from an outpatient diabetes clinic in a single large teaching hospital in Kingston upon Hull, UK. At baseline, demographics and HbA1c were recorded. Patients were categorized by BMI: normal weight (18.5-24.9 kg/m²), overweight (25-29.9 kg/m²), and obese (>30 kg/m²). Multivariable Cox regression models that included demographic, risk factors, and comorbidities were separately constructed for all-cause, cardiovascular, cancer and sepsis-related mortality, using four groups of HbA1c (<6%, 6.0-6.9%, 7.0-7.9%, and >8%).

Results: In total, 6220 patients with T2DM (median age 62 years, 54% male) were followed for a median of 10.6 years. HbA1c levels >8.0% were associated with increased risk of all-cause mortality and cardiovascular death. However, this increased risk was not consistent across the weight categories and reached statistical significance only in overweight patients (BMI 25-29.9 kg/m²).

Conclusions: In a large cohort of patients with T2DM elevated HbA1c levels at baseline did not consistently predict increased risk of all-cause and cardiovascular mortality across the different BMI categories.