THE LONG-TERM INFLUENCE OF INSULIN THERAPY ON THE WEIGHT OF PATIENTS WITH TYPE 2 DIABETES MELLITUS

Abstract

Background and aims. Insulin therapy may determine a sometimes important weight increase in patients with type 2 diabetes mellitus. This side effect can hamper its prescription. The purpose of this work was to study, on long-term (5 years), the weight behavior of patients with type 2 diabetes, started on insulin, and to find out the factors that influence it (age, gender, education, nutritional status, insulin dose and therapeutic scheme). Patients and methods. The study group was composed by 81 patients with type 2 diabetes mellitus, 35 male (43.2%), mean age±SD 56.4±7.4 years (range 34-73 years), followed-up in Diabetes Center Timisoara, who were started on insulin due to poor glycemic control. The body weight was measured yearly for 5 years. The statistical methods used were paired and unpaired t test and linear regression. The threshold for statistical significance for p was considered 0.05. Results. After 5 years, the mean weight increased extremely significant, with 8.2±8 kg, from 77.8±12.5 kg to 86±13.8 kg (p<0.0001). Weight increase was maximal in the first year of insulin therapy (4.4±5.7 kg). According to the weight behavior, 4 subgroups of patients were obtained: a. constant weight or weight loss (n=11, 13.6%);

b. increase <5% from baseline body weight (n=12, 14.8%); c. increase 5-10% (n=16, 19.8%); d. increase >10% (n=42, 51.8%). Between baseline weight and weight gain there was an indirect correlation, extremely significant (r=-0.3666, p=0.0008). The ponderal status (normal weight, overweight, obesity) significantly influenced the further evolution (increase of 19.6±12.7% vs. 11.2±9.5% vs. 7.2±10.4%, respectively, p=0.002). Insulin dose (IU/kg) influenced significantly the weight increase (r=0.4408, p<0.0001), but the therapeutic scheme didn’t seem to have an impact on it. Conclusions. Weight behavior of patients with type 2 diabetes mellitus started on insulin is heterogeneous. The mean body weight increases significantly. The weight gain is the most important in the first year of therapy. It decreases thereafter and reaches a plateau in the 5th year. Weight increase is directly correlated with the dose of insulin and inversely with baseline weight. Consequently, exaggerated fear is not justified in the case of insulin prescription in obese patients with type 2 diabetes mellitus.