Effect of Partial Dietary Replacement From Animal to Plant-Based Protein for Type 2 Diabetes Management

Effect of Partial Dietary Replacement From Animal to Plant-Based Protein for Type 2 Diabetes Management: A Randomized Clinical Trial

The goal of this clinical trial is to examine the effect plant-based diet, with a partial replacement of animal protein by plant protein, in blood sugar levels and other health risks of people with type 2 diabetes and excessive weight. The plant-based diet will be compared to a standard healthy diet according to guidelines for people with diabetes. Participants will follow a plant-based or a standard healthy diet for 24 weeks and will maintain their habitual levels of physical activity.

Study Overview

• Status: Recruiting
• Conditions: Obesity; Overweight; Type 2 Diabetes
• Intervention / Treatment: Behavioral: Control Diet; Behavioral: Plant-based Diet

Detailed Description

This is a single center, open label, parallel and randomized clinical trial. Subjects with type 2 diabetes (T2D) and excessive weight will be recruited through advertisement on the web page of Hospital de Clínicas de Porto Alegre (HCPA), local newspaper, television and social media, or referred by a doctor or nutritionist, from external to HCPA services. Patients will be also screened through electronic records of HCPA's clinics. After screening and selection according to inclusion criteria, participants will undergo a clinical, laboratory and nutritional evaluation following a standard assessment protocol. After all baseline assessments, they will be randomly allocated to one of the following interventions for 24 weeks: (1) Control diet (CDG): hypocaloric diet according to current guidelines for T2D or (2) Plant-based diet (PBG): hypocaloric diet with partial replacement of animal protein by plant protein. Both groups will have caloric targets calculated to achieve a 5% weight loss during the 6 months of study, will have the same macronutrient distribution on the diet and will receive the same nutritional and medical support. Telephone calls will be performed monthly for adherence evaluation. At the end of 12 and 24 weeks of intervention, all patients will be submitted to the same clinical, laboratory and nutrition exams applied at baseline.

• Study Type: Interventional
• Enrollment (Estimated): 146
• Phase: Not Applicable

Contacts and Locations

• Study Contact: Name: Fernando Gerchman, PhD; Phone Number: +555133596246; Email: fgerchman@hcpa.edu.br

Study Locations

• Brazil
  • Rio Grande do Sul
    • Porto Alegre, Rio Grande do Sul, Brazil
      • Recruiting
      • Hospital de Clínicas de Porto Alegre
      • Contact: Fernando Gerchman, PhD; Phone Number: 55 51 33598127; Email: fgerchman@hcpa.edu.br

Participation Criteria

Eligibility Criteria

• Ages Eligible for Study: 18 years to 65 years (Adult, Older Adult)
• Accepts Healthy Volunteers: No

Description

Inclusion Criteria:

• Adults (≥18 and ≤65 years old)
• Diagnosis of Type 2 Diabetes;
• Glycated hemoglobin from 7% to 11%;
• Overweight or obesity (BMI ≥25 kg/m² and <40 kg/m²);
• Use of any hypoglycemic and insulin;
• Stable weight (maximum variation of approximately 5%) for at least 12 weeks before screening;
• Not having undergone dietary intervention in the last 6 months;
• Have the ability to understand and be able to adhere to intervention proposals;
• Able and willing to provide an informed consent form for written and to comply with the requirements of the study protocol;

Exclusion Criteria:

• Type 1 diabetes mellitus;
• Retinopathy with vision deficit that limits the activities proposed in the interventions;
• Chronic kidney disease with estimated glomerular filtration < 30 mL/min per 1.73m²;
• Liver failure, chronic viral hepatitis;
• Grade III or IV heart failure
• Active or progressive neurodegenerative disease;
• Prior stroke that has caused sequelae;
• Use of medications that affect glucose metabolism (e.g. corticosteroids or immunosuppressants) or cause weight loss;
• Chronic treatment with oral or parenteral corticosteroids (>7 days consecutive treatment) within 4 weeks prior to screening;
• Treatment with weight-reducing agents (eg, orlistat, sibutramine, topiramate, bupropion, liraglutide, semaglutide) within the last 12 weeks before screening;
• Treatment with thyroid hormone that was not maintained at a stable dose in last 12 weeks before screening;
• History of active substance abuse (including alcohol) within the last year;
• Thyroid Stimulating Hormone (TSH) outside the normal range;
• Fasting triglycerides ≥ 600 mg/dL;
• Tumor diagnosed and/or treated (except basal cell skin cancer, carcinoma in situ of the cervix, or prostate cancer in situ) within the last 5 years;
• Severe psychiatric illness;
• Predisposition or diagnosis of eating disorders;
• Women who are pregnant, intend to become pregnant during the study period, or who are currently breastfeeding;
• Hyperglycemia characterized by acute symptoms: polyuria, polydipsia and/or weight loss in the last 3 months;
• Metabolic and acute complications of diabetes such as ketoacidosis or hyperosmolar coma;
• Potentially unreliable patients and those deemed by the investigator to be unsuitable for the study;
• Night workers who work after 10pm;
• Being on a vegetarian, vegan or flexitarian diet at the time of recruitment;
• Having undergone bariatric surgery;
• Carriers of the human immunodeficiency virus (HIV);
• Any other medical condition/disorder that the investigators consider that are likely to: interfere with the patient's ability to complete the entire study period or participate in study activities;
• Participants who require any treatment that could affect the interpretation, reliability or safety of data during the study intervention.

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
Active Comparator: Control; Hypocaloric diet with predominance of animal protein	Behavioral: Control Diet; Hypocaloric diet to achieve a 5% weight loss with macronutrient distribution according to current guidelines for T2D: 50% of energy from carbohydrates, prioritizing those with low glycemic index; 30% from total fats and a maximum of 10% from saturated fats; 20% of energy from proteins, 15% from animal sources and 5% from plant sources. Participants will also receive printed and validated educational material, with recommendations for healthy eating, and will be instructed to maintain their habitual physical activity level.
Experimental: Intervention; Hypocaloric diet with predominance of plant protein	Behavioral: Plant-based Diet; Hypocaloric diet to achieve a 5% weight loss. The dietary prescription was adapted from the Eat-Lancet Commission report to Brazilian population culture, with 50% of energy from carbohydrates, prioritizing those with a low glycemic index; 30% from total fats and a maximum of 5% from saturated fats; 20% from proteins, 5% from animal sources and 15% from plant sources. Participants in this group will receive printed and validated support material with recommendations for a healthy and plant-based eating, and will be instructed to maintain their habitual physical activity level.

What is the study measuring?

Primary Outcome Measures

Outcome Measure	Measure Description	Time Frame
Change in Glycated Hemoglobin	Difference between groups in glycated hemoglobin	baseline, 12 and 24 weeks

Secondary Outcome Measures

Outcome Measure	Measure Description	Time Frame
Changes in body composition	Fat-free mass and fat mass will be assessed by Bioelectrical Impedance (body composition analyzer tetrapolar InBody 370S, BiospaceCo. Ltd, Seoul, South Korea). Anthropometric measures include brachial, neck, waist, hip and calf circumferences, with participants wearing light clothing and barefoot.	Monthly, up to 24 weeks
Changes in blood pressure	Blood pressure (mmHg) will be assessed in triplicate with an interval of 1 minute between measurements, with the participant in the sitting position, after 5 minutes of rest. On a subsample, the ambulatory blood pressure monitoring will be used in order to record blood pressure measures in 24 hours and evaluate parameters such as mean BP, pressure loads, areas under the curve, variations between daytime and nighttime, pulse pressure variability	baseline, 12 and 24 weeks
Changes in food craving scale	Food craving will be assessed by the Food Craving Questionnaire-State (FCQ-S), which is composed of 15 statements and is a tool sensitive to changes in contextual, psychological and physiological states in response to specific situations. Higher scores are associated with greater food deprivation, negative eating-related experiences and a greater susceptibility to triggers that lead to eating. Each item has a Likert-response, with (1) totally disagree and (5) totally agree. Total scores vary from 15 to 75 and correspond to the sum of all statements.	baseline, 12 and 24 weeks
Changes in quality of life scale	Quality of life will be measured by the The Short Form 36 Health Survey Questionnaire (the SF-36). SF-36 is a 36 item scale, which measures eight domains of health status: physical functioning (10 items); physical role limitations (four items); bodily pain (two items); general health perceptions (five items); energy/vitality (four items); social functioning (two items); emotional role limitations (three items) and mental health (five items). The scores are transformed to range from zero where the respondent has the worst possible health to 100 where the respondent is in the best possible health.	baseline, 12 and 24 weeks
Changes in depressive symptoms	The Beck Depression Inventory will be used for detecting depressive symptoms, which consists of 21 sets of statements about depressive symptoms in the last 15 days that are rated on a 0 to 3 scale and total scores ranging from 0 to 63. The severity of symptoms will be classified as follows: 0-13, minimal/no depression; 14-19, mild depression; 20-28, moderate depression; and 29-63, severe depression.	baseline, 12 and 24 weeks
Changes in anxiety symptoms	The Generalized Anxiety Symptoms-7 (GAD-7) will be used for assessing anxiety symptoms, which consists of 7 self-reported items. Each item has a Likert-response format on a 4-point scale (0- 3 points). Respondents will be asked to consider the previous 2 weeks and to rate symptom frequency as 'not at all' (0), 'several days' (1), 'more than half of all days' (2) or 'nearly all days' (3). The total score response ranges from 0 to 21.	baseline, 12 and 24 weeks
Glycemic Variability	For continuous glucose monitoring and assessment of glycemic variability, the FreeStyle Libre, ABBOTT® device will be used. FreeStyle Libre consists of a continuous glucose monitoring (SMCG) system. Glycemic variability will be assessed using time on target parameters of values between 70 and 180 mg/dL, time in hypoglycemia and time above target and coefficient of variability as measures of glycemic variability.	baseline and 12 weeks
Changes in postprandial metabolism	Postprandial metabolism will be measured after the intake of liquid standard meal. Insulin secretion, insulin sensitivity and beta-cell function will be assessed by mathematical models	baseline and 12 weeks
Changes in cardiometabolic outcomes	Lipid profile will include total cholesterol, HDL-c, LDL-c, triglycerides, apolipoprotein B, apolipoprotein a1 and lipoprotein (a).	baseline and 24 weeks
Changes in inflammatory marker	Ultra-Sensitive C-Reactive Protein (US-CRP) test will be performed to assess systemic inflammation.	baseline and 24 weeks
Adherence to a plant-based diet	Adherence will be assessed by 7-day weighted food records at 12 and 24 weeks, and by 24-hour food records monthly.	Baseline, 12 and 24 weeks
Incidence of sarcopenia	Incidence of sarcopenia during follow-up among participants without sarcopenia at baseline. Sarcopenia will be defined according to established diagnostic criteria, based on low handgrip strength (muscle strength), low appendicular skeletal muscle mass index (muscle quantity), and impaired physical performance assessed by the Timed Up and Go test	baseline, 12 and 24 weeks
Change in ultra-processed food consumption	Dietary intake will be assessed at baseline and follow-up and classified according to the NOVA food classification system. The outcome is the change in ultra-processed food (UPF) consumption over time. UPF intake will be quantified using complementary metrics, percentage of total energy intake (% energy), absolute energy intake (kcal/day), and amount consumed (g/day), which represent alternative expressions of the same outcome construct.	Baseline, 12, and 24 weeks
Change in estimated glomerular filtration rate	Renal function will be assessed by estimated glomerular filtration rate calculated using the CKD-EPI 2021 equation based on serum creatinine.	Baseline and 24 weeks
Change in albuminuria	Glomerular injury will be assessed by measuring urinary albumin excretion in a 24-hour urine collection and a urine sample. This analysis will be conducted in participants with urinary albumin levels greater than 14 mg/L at baseline.	Baseline, 12 and 24 weeks
Change in bone mineral metabolism parameters	Bone mineral metabolism will be assessed at baseline and follow-up. The outcome is the change in bone mineral metabolism parameters, evaluated using a panel of serum biomarkers including calcium, phosphorus, and 25-hydroxyvitamin D, measured by standard laboratory methods.	Baseline, 12 and 24 weeks

Collaborators and Investigators

• Sponsor: Hospital de Clinicas de Porto Alegre
• Collaborators: Conselho Nacional de Desenvolvimento Científico e Tecnológico
• Investigators: Principal Investigator: Fernando Gerchman, PhD, Hospital de Clínicas de Porto Alegre

Publications and helpful links

General Publications

• Wang YP, Gorenstein C. Psychometric properties of the Beck Depression Inventory-II: a comprehensive review. Braz J Psychiatry. 2013 Oct-Dec;35(4):416-31. doi: 10.1590/1516-4446-2012-1048. Epub 2013 Dec 23.
• Czerwoniuk D, Fendler W, Walenciak L, Mlynarski W. GlyCulator: a glycemic variability calculation tool for continuous glucose monitoring data. J Diabetes Sci Technol. 2011 Mar 1;5(2):447-51. doi: 10.1177/193229681100500236.
• Tai MM. A mathematical model for the determination of total area under glucose tolerance and other metabolic curves. Diabetes Care. 1994 Feb;17(2):152-4. doi: 10.2337/diacare.17.2.152.
• Toumpanakis A, Turnbull T, Alba-Barba I. Effectiveness of plant-based diets in promoting well-being in the management of type 2 diabetes: a systematic review. BMJ Open Diabetes Res Care. 2018 Oct 30;6(1):e000534. doi: 10.1136/bmjdrc-2018-000534. eCollection 2018.
• Moulin CC, Tiskievicz F, Zelmanovitz T, de Oliveira J, Azevedo MJ, Gross JL. Use of weighed diet records in the evaluation of diets with different protein contents in patients with type 2 diabetes. Am J Clin Nutr. 1998 May;67(5):853-7. doi: 10.1093/ajcn/67.5.853.
• Sousa TV, Viveiros V, Chai MV, Vicente FL, Jesus G, Carnot MJ, Gordo AC, Ferreira PL. Reliability and validity of the Portuguese version of the Generalized Anxiety Disorder (GAD-7) scale. Health Qual Life Outcomes. 2015 Apr 25;13:50. doi: 10.1186/s12955-015-0244-2.
• Queiroz de Medeiros AC, Campos Pedrosa LF, Hutz CS, Yamamoto ME. Brazilian version of food cravings questionnaires: Psychometric properties and sex differences. Appetite. 2016 Oct 1;105:328-33. doi: 10.1016/j.appet.2016.06.003. Epub 2016 Jun 7.
• Cruz LN, Fleck MP, Oliveira MR, Camey SA, Hoffmann JF, Bagattini AM, Polanczyk CA. Health-related quality of life in Brazil: normative data for the SF-36 in a general population sample in the south of the country. Cien Saude Colet. 2013 Jul;18(7):1911-21. doi: 10.1590/s1413-81232013000700006.
• Willett W, Rockstrom J, Loken B, Springmann M, Lang T, Vermeulen S, Garnett T, Tilman D, DeClerck F, Wood A, Jonell M, Clark M, Gordon LJ, Fanzo J, Hawkes C, Zurayk R, Rivera JA, De Vries W, Majele Sibanda L, Afshin A, Chaudhary A, Herrero M, Agustina R, Branca F, Lartey A, Fan S, Crona B, Fox E, Bignet V, Troell M, Lindahl T, Singh S, Cornell SE, Srinath Reddy K, Narain S, Nishtar S, Murray CJL. Food in the Anthropocene: the EAT-Lancet Commission on healthy diets from sustainable food systems. Lancet. 2019 Feb 2;393(10170):447-492. doi: 10.1016/S0140-6736(18)31788-4. Epub 2019 Jan 16. No abstract available.

Study record dates

Study Major Dates

• Study Start (Actual): November 1, 2022
• Primary Completion (Estimated): December 30, 2027
• Study Completion (Estimated): December 30, 2027

Study Registration Dates

• First Submitted: December 23, 2022
• First Submitted That Met QC Criteria: January 20, 2023
• First Posted (Actual): January 31, 2023

Study Record Updates

• Last Update Posted (Actual): January 29, 2026
• Last Update Submitted That Met QC Criteria: January 26, 2026
• Last Verified: January 1, 2026

More Information

Terms related to this study

• Keywords: Obesity; Diabetes Mellitus; Insulin Resistance; Plant-based Diet
• Additional Relevant MeSH Terms: Endocrine System Diseases; Nutrition Disorders; Metabolic Diseases; Overnutrition; Body Weight; Glucose Metabolism Disorders; Hyperinsulinism; Pathological Conditions, Signs and Symptoms; Nutritional and Metabolic Diseases; Signs and Symptoms; Overweight; Obesity; Diabetes Mellitus, Type 2; Diabetes Mellitus; Insulin Resistance; Therapeutics; Diet, Food, and Nutrition; Physiological Phenomena; Nutritional Physiological Phenomena; Diet Therapy; Nutrition Therapy; Diet; Diet, Plant-Based
• Other Study ID Numbers: 2020-0095

Plan for Individual participant data (IPD)

• Plan to Share Individual Participant Data (IPD)?: NO

Drug and device information, study documents

• Studies a U.S. FDA-regulated drug product: No
• Studies a U.S. FDA-regulated device product: No
• product manufactured in and exported from the U.S.: No