Metabolic Effects of a Low Carbohydrate Versus a Standard Diet in Morbidly Obese With Prediabetes (CaPrO)

Metabolic Effects of a Low Carbohydrate Versus Energy-matched Standard Diet in Morbidly Obese Individuals With Prediabetes

To investigate the metabolic effects of a low carbohydrate versus energy-matched standard diet in morbidly obese individuals with prediabetes awaiting bariatric surgery.

Study Overview

• Status: Completed
• Conditions: PreDiabetes; Obesity, Morbid; Bariatric Surgery Candidate
• Intervention / Treatment: Other: Low carbohydrate diet; Other: Energy-matched standard diet

Detailed Description

The metabolic benefits of calorie restriction in obese people with or without impaired glycaemia are well-established. The impact of diet composition, however, remains poorly understood. Hepatic lipid content strongly correlates with hepatic insulin resistance, which is a key feature of the pre-diabetic state. The investigators hypothesize that a low carbohydrate diet compared to an energy-matched standard diet in morbidly obese patients with prediabetes scheduled for bariatric surgery results in greater reduction in liver fat.

• Study Type: Interventional
• Enrollment (Actual): 20
• Phase: Not Applicable

Contacts and Locations

Study Locations

• Switzerland
  • Bern, Switzerland, 3010
    • Division of Endocrinology, Diabetes and Clinical Nutrition, Bern University Hospital

Participation Criteria

Eligibility Criteria

• Ages Eligible for Study: 18 years and older (Adult, Older Adult)
• Accepts Healthy Volunteers: No

Description

Inclusion Criteria:

• Female and male subjects aged 18 years or older
• BMI >35 kg/m2 awaiting bariatric surgery
• Pre-diabetes according to American Diabetes Association criteria (HbA1c 5.7%-6.4%)
• Capacity to give informed consent and adhere to study procedures

Exclusion Criteria:

• Excess alcohol consumption (> 3 units/day for men, > 2 units/day for women)
• Moderate to severe kidney disease
• Nephrolithiasis
• Pregnancy/breastfeeding
• Current participation in another clinical trial
• Claustrophobia
• MRI-contraindications (pacemaker/defibrillator, neurostimulator, drug pump, cochlear implant, heart valve/vascular clips, shunt valve)

Study Plan

How is the study designed?

Design Details

• Primary Purpose: Treatment
• Allocation: Randomized
• Interventional Model: Parallel Assignment
• Masking: Single

Number of Arms

2

Arms and Interventions

Participant Group / Arm	Intervention / Treatment
Experimental: Study intervention; Participants will follow an energy deficient (30% deficit) low carbohydrate diet (10% of carbohydrates) for minimum two weeks.	Other: Low carbohydrate diet; A energy deficient (30% deficit) low carbohydrate diet (10% of carbohydrates)
Active Comparator: Control intervention; Participants will follow an energy deficient (30% deficit) standard diet (50% of carbohydrates) for minimum two weeks.	Other: Energy-matched standard diet; Energy-matched (30% deficit) standard diet (50% of carbohydrates)

What is the study measuring?

Primary Outcome Measures

Outcome Measure	Measure Description	Time Frame
Change from baseline in intrahepatic triglyceride content	The intrahepatic triglyceride content will be evaluated by magnetic resonance spectroscopy	2 weeks

Secondary Outcome Measures

Outcome Measure	Measure Description	Time Frame
Change from baseline in body weight	The body weight will be measured using a pre-defined person scale	2 weeks
Change from baseline in liver size	The liver size will be evaluated by magnetic resonance imaging	2 weeks
Change from baseline in visceral adipose tissue	The adipose tissue content will be evaluated by magnetic resonance imaging	2 weeks
Change from baseline in whole body fat mass	Fat mass will be evaluated by bioimpedance	2 weeks
Change from baseline in insulin secretion	The insulin secretion will be evaluated during an oral glucose tolerance test using the oral minimal model	2 weeks
Change from baseline in insulin sensitivity	The insulin sensitivity will be evaluated during an oral glucose tolerance test using the oral minimal model	2 weeks

Other Outcome Measures

Outcome Measure	Measure Description	Time Frame
Change from baseline in plasma metabolome	Fasting serum sampling	2 weeks
Change from baseline in plasma transcriptome	Fasting serum sampling	2 weeks
Change from baseline in Fibroblast Growth Factor 21	Plasma level	2 weeks
Change from baseline in adipose tissue inflammation	Adipose tissue histology	2 weeks
Change from baseline in gut microbiota composition	Distribution of the predominant bacterial phylotypes will be assessed after 16S rRNA amplicon sequencing and subsequent taxonomic classification	2 weeks
Change from baseline levels of secondary bile acids	Faecal sampling	2 weeks
Change in frequency of immune cells (T-, B-, NK-cells, monocytes, neutrophils)	Frequency of immune cells will be analysed using flowcytometry	2 weeks
Change in immunometabolism of T-cells	Immunometabolism will be assessed by quantifying rates of oxygen consumption and glycolysis using metabolic flux analysis	2 weeks
Occurrence of surgical complication	Occurrence of the following: anastomotic leak, infection, bleeding, deep venous thrombosis (based on medical records)	Day of surgery until 2 weeks post-surgery
Length of hospital stay	Based on medical records	Day of surgery until 2 weeks post-surgery

Collaborators and Investigators

• Sponsor: Insel Gruppe AG, University Hospital Bern
• Investigators: Principal Investigator: Lia Bally, MD PhD, Inselspital, Bern University Hospital, University of Bern

Study record dates

Study Major Dates

• Study Start (Actual): May 13, 2019
• Primary Completion (Actual): May 3, 2024
• Study Completion (Actual): May 3, 2024

Study Registration Dates

• First Submitted: March 7, 2019
• First Submitted That Met QC Criteria: March 15, 2019
• First Posted (Actual): March 19, 2019

Study Record Updates

• Last Update Posted (Actual): December 9, 2024
• Last Update Submitted That Met QC Criteria: December 4, 2024
• Last Verified: December 1, 2024

More Information

Terms related to this study

• Keywords: Prediabetes; Bariatric Surgery; Low-carb diet
• Additional Relevant MeSH Terms: Endocrine System Diseases; Nutrition Disorders; Metabolic Diseases; Overnutrition; Body Weight; Glucose Metabolism Disorders; Diabetes Mellitus; Overweight; Obesity; Hyperglycemia; Obesity, Morbid; Prediabetic State; Glucose Intolerance
• Other Study ID Numbers: CaPrO

Drug and device information, study documents

• Studies a U.S. FDA-regulated drug product: No
• Studies a U.S. FDA-regulated device product: No