Semaglutide once weekly as add-on to SGLT-2 inhibitor therapy in type 2 diabetes (SUSTAIN 9): a randomised, placebo-controlled trial

Lancet Diabetes Endocrinol. 2019 May;7(5):356-367. doi: 10.1016/S2213-8587(19)30066-X. Epub 2019 Mar 1.


Background: Semaglutide is a once-weekly glucagon-like peptide-1 (GLP-1) analogue for type 2 diabetes. Few clinical trials have reported on the concomitant use of GLP-1 receptor agonists with sodium-glucose cotransporter-2 (SGLT-2) inhibitors. We aimed to investigate the efficacy and safety of semaglutide when added to SGLT-2 inhibitor therapy in patients with inadequately controlled type 2 diabetes.

Methods: The SUSTAIN 9 double-blind, parallel-group trial was done at 61 centres in six countries (Austria, Canada, Japan, Norway, Russia, and the USA). Adults with type 2 diabetes and HbA1c 7·0-10·0% (53-86 mmol/mol), despite at least 90 days of treatment with an SGLT-2 inhibitor, were randomly assigned (1:1) to receive subcutaneous semaglutide 1·0 mg or volume-matched placebo once weekly for 30 weeks, after a dose-escalation schedule of 4 weeks of 0·25 mg semaglutide or placebo and 4 weeks of 0·5 mg semaglutide or placebo. Existing antidiabetic medications, including SGLT-2 inhibitor treatment, were continued for the duration of the trial. Rescue medication, defined as intensification of background antidiabetic treatment or the initiation of new glucose-lowering medications, could be given to patients meeting specific criteria at the discretion of the investigator. The primary outcome was change in HbA1c from baseline at week 30, assessed in the full analysis set (all patients randomly allocated to treatment) using on-treatment data collected before rescue medication was started. The confirmatory secondary outcome was change in bodyweight from baseline to week 30. Safety was also assessed in the safety analysis set (all patients who received at least one dose of treatment). The trial was registered with (NCT03086330).

Findings: Between March 15, and Dec 4, 2017, 302 patients were enrolled and randomly assigned to receive semaglutide 1·0 mg or placebo (full analysis set), of whom 301 received at least one dose of treatment (safety analysis set). One patient was assigned to semaglutide but was not treated (reason unknown). 294 (97·4%) patients completed the trial and 267 (88·4%) completed treatment. Baseline characteristics were generally comparable between groups. In addition to randomised medication and SGLT-2 inhibitor, 216 (71·5%) patients were taking metformin and 39 (12·9%) were taking sulphonylurea. Patients given semaglutide had greater reductions in HbA1c (estimated treatment difference -1·42% [95% CI -1·61 to -1·24]; -15·55 mmol/mol [-17·54 to -13·56]) and bodyweight (-3·81 kg [-4·70 to -2·93]) versus those randomised to placebo (both p<0·0001). 356 adverse events were reported by 104 (69·3%) patients in the semaglutide group, and 247 adverse events were reported by 91 (60·3%) patients in the placebo group. Gastrointestinal adverse events were most common and were reported in 56 (37·3%) patients in the semaglutide group and 20 (13·2%) in the placebo group. Serious adverse events occurred in seven (4·7%) patients in the semaglutide group and six (4·0%) in the placebo group. Severe or blood glucose-confirmed hypoglycaemic events were reported in four patients on semaglutide (2·7%). 16 patients stopped treatment early because of an adverse event, 13 of whom were in the semaglutide group. There were no deaths during the trial.

Interpretation: Adding semaglutide to SGLT-2 inhibitor therapy significantly improves glycaemic control and reduces bodyweight in patients with inadequately controlled type 2 diabetes, and is generally well tolerated.

Funding: Novo Nordisk.

Publication types

  • Clinical Trial, Phase III
  • Multicenter Study
  • Randomized Controlled Trial
  • Research Support, Non-U.S. Gov't

MeSH terms

  • Adult
  • Aged
  • Diabetes Mellitus, Type 2 / blood
  • Diabetes Mellitus, Type 2 / drug therapy*
  • Diabetes Mellitus, Type 2 / epidemiology
  • Double-Blind Method
  • Drug Administration Schedule
  • Drug Therapy, Combination
  • Female
  • Glucagon-Like Peptides / administration & dosage*
  • Glucagon-Like Peptides / adverse effects
  • Humans
  • Hypoglycemic Agents / administration & dosage*
  • Hypoglycemic Agents / adverse effects
  • Male
  • Middle Aged
  • Placebos
  • Sodium-Glucose Transporter 2 Inhibitors / administration & dosage*
  • Sodium-Glucose Transporter 2 Inhibitors / adverse effects
  • Treatment Outcome


  • Hypoglycemic Agents
  • Placebos
  • Sodium-Glucose Transporter 2 Inhibitors
  • semaglutide
  • Glucagon-Like Peptides

Associated data