Background: Bone fragility is a complication of type 2 diabetes. Diabetes treatments may ameliorate or deteriorate bone fragility in this population. Bariatric surgery is gaining in popularity in people with type 2 diabetes and may impact bone health. Objectives: To evaluate the impact of the most popular bariatric procedure worldwide (sleeve gastrectomy (SG)) on vBMD by QCT in patients with type 2 diabetes; Secondary aims: (1) to identify the determinants of vBMD after bariatric surgery in patients with type 2 diabetes; (2) to compare vBMD and its potential determinants after bariatric surgery with obese controls without diabetes as well as with controls without obesity and normoglycemia.

This is a multicentre, prospective and observational study comprising a bariatric group with or without diabetes undergoing SG (n=70) and one control group (n=30).

Outcome measures are assessed before and at 4 months, 8 months, one year and 3 years after surgery in the bariatric groups and at a single visit for the control group.

Bariatric groups will include adult men and women with or without type 2 diabetes and obesity undergoing sleeve gastrectomy and followed at 0, 4 months, 8 months, 1 year and 3 years after surgery, and the control group will consist of 30 overweight individuals (10 men, 10 premenopausal women, 10 menopausal women) and without diabetes or prediabetes and assessed at a single visit.

Inclusion Criteria:

• bariatric groups: men and women; 18 to 60 years old; with a BMI >=35 kg/m2; with type 2 diabetes: use of oral hypoglycemic agents or insulin OR 2 of the following tests confirming type 2 diabetes: HbA1c >=6.5%; fasting glucose >=7.0 mM; 2-h glucose post 75g oral glucose tolerance test (OGTT) >=11.1 mM) (guidelines.diabetes.ca);) or without diabetes: HbA1c <6.5% AND fasting glucose <7.0 mM; who are awaiting bariatric surgery. Control group: BMI 25.0 to 29.9 kg/m2 (overweight group); without diabetes or prediabetes: HbA1c <6.0% AND fasting glucose <6.1 mM (Diabetes Canada criteria), with a stable weight for the last 3 months.

Exclusion Criteria:

• bariatric groups: type 1 diabetes; disease (e.g. uncontrolled thyroid disease, malabsorptive or overt inflammatory disorder, metabolic bone disease, creatinine clearance <60 ml/min) or medication (e.g. glucocorticoids, anti-epileptic drugs, osteoporosis therapy and thiazolidinediones) affecting bone metabolism; BMI>60 kg/m2; CT scan impossible to perform (e.g. patient too large for the gantry aperture); pregnant women or women who plan to become pregnant during the study or women of childbearing age who do not agree to take an appropriate contraceptive method during the study; history of oesophageal, gastric or digestive surgery; history of bariatric surgery; cancer at risk of recurrence during the study; Prosthesis that could interfere with interpretation of imaging data; Chronic severe condition or illness precluding from participation in the project.

Control group: Same criteria plus: >5% change in weight in the last 3 months; pregnancy or lactation in the last year.

This is a multicentre, prospective and observational study comprising a bariatric group with or without diabetes undergoing SG (n=70) and one control group (n=30).

Bariatric groups will include adult men and women with or without type 2 diabetes and obesity undergoing sleeve gastrectomy and followed at 0, 4 months, 8 months, 1 year and 3 years after surgery, and the control group will consist of 30 overweight individuals (10 men, 10 premenopausal women, 10 menopausal women) and without diabetes or prediabetes and assessed at a single visit.