Insulin-Induced Edema in a Patient with Type 2 Diabetes Mellitus

BACKGROUND The strong association between type 2 diabetes and obesity has been well recognized. Insulin treatment is usually needed at some point in the treatment of patients with type 2 diabetes and obesity to achieve the targeted glycemic control goal. CASE REPORT A 35-year-old woman who had gastric banding for morbid obesity 1 year prior presented to the outpatient clinic with recent onset of shortness of breath and bilateral ankle edema, which were thought to be of cardiac origin. Band slippage occurred a few months after the procedure, and the patient gained weight rapidly thereafter. She had been diagnosed with type 2 diabetes mellitus 8 years earlier, which was treated with oral hypoglycemic medication. Thyroid function tests done 4 months prior to her current presentation revealed normal results. A cardiac assessment showed normal cardiac function with no evidence of heart failure. Repeated thyroid function testing showed new-onset subclinical hypothyroidism. The patient had started insulin therapy 2 weeks before her current presentation, which was probably the main cause of her edema. While continuing insulin, the patient's general condition improved with diuretics therapy, following which she had gastric bypass surgery. CONCLUSIONS Insulin-induced edema is an under-diagnosed problem. It should be considered whenever a patient with uncontrolled diabetes develops rapid body swelling after initiation of insulin therapy. Rigorous research is needed to explore the pathophysiology, prevalence, and treatment of insulin-induced edema.