A Retrospective Analysis of Insulin Dose in Relation to Body Weight and Glycaemic Control Among Patients with Type 2 Diabetes Mellitus

Purpose: The progressive nature of Type 2 diabetes mellitus (T2DM) due to declining pancreatic β-cell function frequently requires insulin dose optimization and intensification, resulting in high total daily doses (TDD) of insulin in clinical practice. However, evidence evaluating the relationship between TDD, body weight, and glycaemic control remains limited. Methods: A retrospective cohort study was conducted among adults with T2DM receiving insulin therapy at two primary health clinics between 2020 and 2023 (N=90). Patients were categorised into standard-dose insulin (SDI, n=44) and high-dose (HDI, n=46) insulin groups. The outcomes measured were changes in body weight and follow-up HbA1c. An independent-samples t test was performed to compare outcomes between dose groups and multivariable analyses was conducted to identify factors associated with body weight change and HbA1c. Results: Patients in the SDI group had a smaller mean body weight change than those in the HDI group (3.07±4.90 vs 5.57±6.69kg; mean difference −2.50 kg, 95% CI −4.95 to −0.05; p = 0.045). Mean follow-up HbA1c was higher in the HDI group (10.39±1.86%) compared with the SDI group (9.55±1.95%), with a between-group difference of −0.84% (95% CI −1.64 to −0.04; p = 0.040). TDD and pre-insulin body weight showed statistically significant associations with body weight change. Age, use of metformin and dipeptidyl peptidase-4 (DPP-4) inhibitors, insulin analogue, and mixed human/analogue regimens showed statistically significant associations with HbA1c. Conclusion: Higher insulin doses were associated with greater body weight change and higher HbA1c. However, prospective studies are needed to clarify temporal relationships and to formulate insulin optimization strategies.