Isolated and Combined Effect of a Low Carbohydrate Diet and Exercise in Hypoxia in Patients With Type 2 Diabetes

Not Applicable

Completed

• Conditions: Carbohydrate; Diabetes Mellitus, Type 2; Exercise; Hypoxia
• Interventions: Other: Exercise in normoxia; Other: Exercise in hypoxia; Other: Control diet; Other: Low carbohydrate diet

• Registration Number: NCT05094505
• Lead Sponsor: Universidade do Porto

Brief Summary

The purpose of this study is to determine the effects of isolated chronic exercise in hypoxia and combined exercise in hypoxia with a low carbohydrate diet on hypoxia-induced transcription factor (HIF1-α); glycaemic control and cardiovascular risk factors in patients with type 2 diabetes.

Detailed Description

At baseline, diet plans will be individualized and energy-content prescriptions will be constant throughout the study to maintain the isocaloric control between diets. The planned macronutrient compositions will be, 30% of energy from carbohydrates, 20% from protein and 50% from fat for low carbohydrate diet (LCD) and 30% of energy from fat, 20% from protein and 50% from carbohydrates for the low-fat diet (control diet), during the 8 weeks. Both diets emphasis on low-glycemic index foods and limited saturated fat to 10% of energy, and calculated with appropriate software.

Exercise in hypoxia (at 3000m altitude, 3 sessions/week) will occur during a 8-week period intervention and all testing sessions carried out in a hypoxic chamber at Exercise Medical Center, Porto - Portugal. This chamber allows control of O2 (11-20.97%), temperature (until 50ºC), humidity (until 80%) and altitude (until 8000m). Exercise in hypoxia sessions will consist in 60 min on an ergometer (Excalibur, Lode, Netherlands) of continuous moderate and high intensity interval training, these latter considered as an efficient strategy to improve cardiorespiratory and metabolic health in patients with type 2 diabetes. Loads will be quantified according to pre-intervention testing assessments and controlled throughout each training session. All exercise testing and training sessions will be carried out at the same time of day (± 2 hours) and visits will be separated by at least 48h of recovery.

Height will be measured with use of a stadiometer (SECA), waist circumference was measured by using a tape measure positioned 3 cm above the iliac crest. Body mass index (BMI), weight, fat mass (FM) and fat-free mass (FFM) were determined by using whole-body dual-energy X-ray absorptiometry (Lunar Prodigy; General Electric Corp.). Blood pressure will be measured by using an automated sphygmomanometer (Dinamap Pro; Medical Systems,Tampa, FL) and haematological adaptations will be measured by collecting a venous blood sample from a vein in the arm using a needle. A total of 3 blood samples (pre, 1h post first intervention testing and 48h post the last intervention testing) will be taken.

Study Timeline

• Study First Submitted: 2021-09-15
• Study Start: 2021-10-01
• Study First Submitted QC: 2021-10-13
• Study First Posted: 2021-10-26
• Status Verified: 2023-07
• Primary Completion: 2023-07-18
• Study Completion: 2023-07-18
• Last Update Submitted: 2023-07-18
• Last Update Posted: 2023-07-19

Recruitment & Eligibility

• Status: COMPLETED
• Sex: All
• Target Recruitment: 42

Inclusion Criteria

• Diagnosis of type 2 diabetes for at least one year
• Glycosylated haemoglobin less than 10%
• Pharmacological regimen stabilized for at least three months
• Main complications of diabetes tracked and controlled (diabetic retinopathy, diabetic nephropathy, diabetic foot and main factors of cardiovascular risk)
• Previous participation in supervised exercise programs in the last 3 months
• Smoking absence in the last 6 months.

Exclusion Criteria

• Diagnosis of type 2 diabetes for less than a year
• Glycosylated haemoglobin above 10%
• Pharmacological regimen less than three months
• Main complications of diabetes (diabetic retinopathy, diabetic nephropathy, diabetic foot and main factors of cardiovascular risk)
• Sedentary participants
• Smoking participants

Study & Design

• Study Type: INTERVENTIONAL
• Study Design: PARALLEL

Arm && Interventions

Group	Intervention	Description
Ex. Hyp. GROUP	Exercise in hypoxia	Exercise in hypoxia at 3000m altitude. Control diet.
CONTROL GROUP	Control diet	Exercise at sea level, normoxia. Control diet.
Ex. Hyp. GROUP	Control diet	Exercise in hypoxia at 3000m altitude. Control diet.
Ex. Hyp. + LCD GROUP	Exercise in hypoxia	Exercise in hypoxia at 3000m altitude. Low carbohydrate diet.
CONTROL GROUP	Exercise in normoxia	Exercise at sea level, normoxia. Control diet.
Ex. Hyp. + LCD GROUP	Low carbohydrate diet	Exercise in hypoxia at 3000m altitude. Low carbohydrate diet.

Primary Outcome Measures

Name	Time	Method
Changes from pre- to pos intervention on glycated haemoglobin	Baseline and week 8	A venous blood sample from the arm will be collected and glycated hemoglobin will be measured and expressed in mmol/mol and as a percentage (%).

Secondary Outcome Measures

Name	Time	Method
Changes from pre- to post intervention in insulin resistance index and β-cell capacity	Baseline and week 8	A venous blood sample from the arm will be collected and fasting blood glucose (mg/dL) and fasting blood insulin (micro international unit/dL) will be measured, which will determine the homeostasis model assessment (mmol/dL) and homeostasis model assessment 2 for β-cell function (%).
Changes from pre- to pos intervention in angiogenesis	Baseline and week 8	A venous blood sample from the arm will be collected and, serum Hypoxia Inducible Factor 1 alpha (HIF1-α) will be measured using specific ELISA kit instructions.

Trial Locations

Locations (2)

University of Porto; 🇵🇹 Porto, Portugal

University of Maia; 🇵🇹 Porto, Portugal