Glycemic Variability After SASI Versus Roux-en-Y Gastric Bypass

• Single Anastomosis Sleeve Ileal Bypass (Procedure): Bariatric surgical procedure consisting of sleeve gastrectomy with a single gastroileal anastomosis.
• Roux-en-Y Gastric Bypass (Procedure): Bariatric surgical procedure consisting of gastric pouch creation with gastrojejunal and jejunojejunal anastomoses.

Primary outcomes

• Glycemic Variability Assessed by Glucose Coefficient of Variation [Baseline, 6 months, and 12 months after surgery]: Glycemic variability will be assessed using the glucose coefficient of variation (CV), calculated from 7 days of continuous glucose monitoring as the standard deviation of glucose divided by mean glucose concentration × 100. CV will be assessed at baseline, 6 months, and 12 months after surgery and compared between the SASI and Roux-en-Y gastric bypass groups.

Secondary outcomes

• Hypoglycemic Events Detected by Continuous Glucose Monitoring [Baseline, 6 months, and 12 months after surgery]: Number and frequency of symptomatic and asymptomatic hypoglycemic events detected during 7 days of continuous glucose monitoring. Symptomatic events will also be recorded using the participant event diary.
• Body Mass Index [Baseline, 3 months, 6 months and 12 months after surgery]: Body mass index (BMI) will be calculated as body weight in kilograms divided by height in meters squared (kg/m²).
• Patient-Reported Outcomes Assessed by BODY-Q [Baseline, 6 months, and 12 months after surgery]: Patient-reported outcomes related to quality of life and body image will be assessed using the BODY-Q questionnaire.
• Gastroesophageal Reflux Symptoms Assessed by GERD-Q [Baseline, 6 months, and 12 months after surgery]: Gastroesophageal reflux symptoms will be assessed using the GERD-Q questionnaire.
• Eating Behavior Assessed by TFEQ-R18 [Baseline, 6 months, and 12 months after surgery]: Eating behavior will be assessed using the Three-Factor Eating Questionnaire-Revised 18-item version (TFEQ-R18).
• Change in Type 2 Diabetes Mellitus Status [Baseline, 3 months, 6 months, and 12 months after surgery]: Changes in type 2 diabetes mellitus will be assessed using glycated hemoglobin (HbA1c) levels and changes in the requirement for insulin or oral glucose-lowering medications.
• Change in Hypertension Status [Baseline, 3 months, 6 months, and 12 months after surgery]: Changes in hypertension will be assessed based on blood pressure measurements and changes in antihypertensive medication requirements.
• Change in Dyslipidemia Status [Baseline, 3 months, 6 months, and 12 months after surgery]: Changes in dyslipidemia will be assessed based on serum lipid profile, including cholesterol and triglyceride levels, and changes in lipid-lowering medication requirements.
• Nutritional Deficiencies [Baseline, 3 months, 6 months, and 12 months after surgery]: Nutritional status will be assessed using serum levels of iron, calcium, vitamin D, and vitamin B12.
• Postoperative Complications [From surgery through 12 months after surgery]: Incidence of postoperative complications, including gastroesophageal reflux, anastomotic leak, stenosis, and severe hypoglycemic episodes, will be recorded during follow-up.
• Percentage of Excess Weight Loss [3 months, 6 months, and 12 months after surgery]: Weight loss will be assessed as the percentage of excess weight loss (%EWL) after bariatric surgery.
• Percentage of Total Weight Loss [3 months, 6 months, and 12 months after surgery]: Weight loss will be assessed as the percentage of total weight loss (%TWL) from baseline body weight.
• Mean Amplitude of Glycemic Excursions [Baseline, 6 months, and 12 months after surgery]: Mean amplitude of glycemic excursions (MAGE) will be calculated from continuous glucose monitoring data as a measure of short-term intraday glycemic variability.
• Time in Range [Baseline, 6 months, and 12 months after surgery]: Time in range (TIR) will be calculated from continuous glucose monitoring data as the percentage of time that glucose values are between 70 and 180 mg/dL.
• Mean Glucose Concentration [Baseline, 6 months, and 12 months after surgery]: Mean glucose concentration will be calculated from continuous glucose monitoring data collected over 7 days at each study time point.
• Glucose Standard Deviation [Baseline, 6 months, and 12 months after surgery]: Glucose standard deviation will be calculated from continuous glucose monitoring data collected over 7 days at each study time point as a measure of short-term intraday glycemic variability.

Sex: All, ages: 18 Years to 74 Years

Inclusion Criteria:

* Age 18 years or older and younger than 75 years.
* Morbid obesity with body mass index (BMI) between 35 and 55 kg/m².
* Pre-anesthetic assessment classified as ASA I-III.
* Signed informed consent.

Exclusion Criteria:

* Body mass index (BMI) >55 kg/m².
* Previous major gastrointestinal surgery.
* Diseases that alter interstitial fluid volume and may affect glucose measurement accuracy, including severe acute or chronic renal failure, heart failure, or liver failure.
* Pathological gastroesophageal reflux disease with endoscopic involvement.
* Pre-anesthetic assessment not suitable for surgery or ASA IV.
* Pregnancy.
* Alcohol addiction.
* Active malignancy.
* Refusal to sign informed consent.
* Inability to comply with study instructions.'

• Isaías Alarcón del Agua, MD, PhD, Principal investigator, Hospitales Universitarios Virgen del Rocío