Severe obesity in a specialist type 2 diabetes outpatient clinic: an Australian retrospective cohort study

BACKGROUND: Obesity is a major risk factor for the development of type 2 diabetes (T2DM) and its complications. Significant weight loss has been shown to improve glycaemia in people with T2DM and obesity. National and international guidelines recommend considering bariatric surgery for body mass index (BMI) ≥ 35 kg/m(2). We assessed the proportion of people with T2DM meeting criteria for surgery, how many had been offered a bariatric/obesity service referral, and compared the characteristics of people with BMI ≥ 35 kg/m(2) and BMI < 35 kg/m(2). METHODS: Retrospective data were collected for all people with T2DM aged ≥18 years, attending a hospital specialist diabetes outpatient service over three calendar years, 2017–2019. RESULTS: Of 700 people seen in the service, 291 (42%) had BMI ≥ 35 kg/m(2) (the “BMI ≥ 35 group”) and met criteria for bariatric surgery, but only 54 (19%) of them were offered referral to an obesity service. The BMI ≥ 35 group was younger than those with a BMI < 35 kg/m(2) (56.1 ± 14.8 vs 61.4 ± 14.6 years, p < 0.001) (mean ± SD), with similar diabetes duration (11.0 ± 9.0 vs 12.3 ± 8.9 years, p = 0.078), and there was no significant difference in initial HbA1c (75 ± 27 vs 72 ± 26 mmol/mol, p = 0.118) (9.0 ± 2.5 vs 8.7 ± 2.4%) or proportion treated with insulin (62% vs 58%). There was more GLP1 agonist use in the BMI ≥ 35 group (13% vs 7%, p = 0.003) but similar rates of SGLT2 inhibitor use (25% vs 21%, p = 0.202). The BMI ≥ 35 group received more new medication and/or dose adjustments (74% vs 66%, p = 0.016). Only 29% in the BMI ≥ 35 kg group achieved HbA1c < 53 mmol/mol (7.0%). CONCLUSIONS: In spite of frequently meeting the criteria for bariatric surgery and not achieving glycaemic targets, people with T2DM in this specialist clinic received limited medical or surgical management of their obesity. This study suggests opportunities for improvement in care of people with T2DM at several levels including increased referrals from T2DM services to weight management/bariatric services, as well as an increased use of GLP1 agonists and SGLT2 inhibitors where appropriate. Our data support the need to prioritise obesity management in the treatment of type 2 diabetes.