Effectiveness of Sodium-Glucose Cotransporter-2 Inhibitor as an Add-on Drug to GLP-1 Receptor Agonists for Glycemic Control of a Patient with Prader-Willi Syndrome: A Case Report

Abstract

Introduction: Diabetes patients with Prader-Willi syndrome (PWS) are obese because of hyperphagia; weight control by dietary modification and medicine is required for glycemic control. There are several recent reports showing the effectiveness of GLP-1 receptor agonists (GLP-1RAs) for diabetes treatment in PWS.

Case report: A 36-year-old Japanese male patient was diagnosed with PWS at 10 years of age. At age 16 years, he was diagnosed with diabetes and began to take several kinds of oral hypoglycemic agents. At age 29 years, his BMI was 39.1 kg/m² and he was referred to our department for diabetes and obesity treatment. In the present case, the HbA1c was not improved by GLP-1RAs despite a 28-kg BW reduction, which included a 9-kg loss of muscle. Apprehensive of further loss of muscle mass, basal insulin of insulin glargine was administered in addition to GLP-1RAs. Immediately after the addition of tofogliflozin, a sodium-glucose cotransporter-2 (SGLT2) inhibitor, the patient's HbA1c decreased dramatically with only about an additional 3% BW reduction. We note an improvement in our case of lipid deposition in the pancreas confirmed by abdominal CT after the improvement of HbA1c. It is unknown whether this improvement of fatty pancreas was a cause or an effect of the improved glycemic control in the present case.

Conclusion: This finding clearly supports the effectiveness of combining SGLT2 inhibitors with GLP-1RAs for treatment of patients with PWS and non-alcoholic fatty pancreas disease.

Keywords: GLP-1 receptor agonists (GLP-1RAs); Non-alcoholic fatty pancreas disease (NAFPD); Prader–Willi syndrome (PWS); Sodium-glucose cotransporter-2 (SGLT2) inhibitor.

Fig. 1

Course of treatment graph showing the corresponding effects on weight and HbA1c. The duration of pharmacological agents is represented by the length of each box relative to the time period on the x-axis. Changes in HbA1c are shown by the black line plotted against the y-axis (left) and changes in weight are shown by the gray dotted line plotted against the y-axis (right). The black downward arrow indicates the time when tofogliflozin was begun. The white open arrows indicate hospitalization for glycemic control. Periodical change of body composition measurement was also shown in the lower panel

Fig. 2

Abdominal CT findings at 28 years (a) and 35 years (b) of age. a Abdominal CT imaging showing the presence of diffuse fat infiltration from the head to tail of the pancreas. b Relative to a, pancreatic normal tissue can be distinguished from the surrounding fat. The subcutaneous fat area has obviously declined