Meal Replacement in Dietary Management of Type-2 Diabetes Mellitus: A Scoping Review Protocol

DOI: https://doi.org/10.21203/rs.3.rs-17283/v1

Abstract

Background: The prevalence of type 2 diabetes mellitus (T2DM) has been increasing globally. Without proper management, T2DM can develop into serious complications and even death. Diet modification is one of the most effective tool in managing T2DM patients but it requires knowledge and compliance from the patients. Thus, meal replacement (MR) has gained its popularity as a tool for diet modification to improve glycemic control and also reducing weight in T2DM patients. There are several existing meal replacement studies but not much is known on the general scope and effect of these existing MRs. Hence, this review is aimed to provide an overview of the existing evidences regarding the application of meal replacement on T2DM patients and identify the gaps or limitation in the studies.

Methodology: The scoping review will be carried out in six stages. (1) identifying the research question, (2) identifying relevant studies through electronic databases (ie. Pubmed, Scopus, Cochrane Reviews, Google Scholar, EBSCOHOST, Science Direct) and also grey literature, (3) selection of studies to be included based on inclusion criteria. Search and initial screening of studies to be included will be conducted by two independent reviewers. Discrepancies will then be solved through discussion with other reviewers, (4) Chart and categorize extracted data in a pretested data extraction form, (5) collating, summarising and reporting the results and lastly, (6) conducting consultation with stakeholders and experts in diabetes.

Discussion: This scoping review protocol is aimed to provide a framework enabling us to map and summarize the findings from existing studies involving meal replacement. It will help researchers to identify research gap and provide recommendations for future meal replacement studies. The results from this scoping review will be useful to various stakeholders in healthcare. It is also part of a research project in which the information obtained will be utilized in clinical trial of a developed meal replacement plan. Dissemination of knowledge will also be done through presentations at T2DM related conferences.

Background

Diabetes mellitus is an epidemic public health threat affecting people worldwide. The International Diabetes Federation (IDF) estimated that global prevalence of diabetes mellitus is 451 million in 2017 and projected to increase to 693 million by 2045.[1] Among them, over 90% of diabetes mellitus cases are Type 2 diabetes mellitus (T2DM).[2] Type 2 diabetes mellitus is a chronic metabolic disorder which is previously known as non-insulin dependent diabetes mellitus. It is the most common form of diabetes mellitus characterized by hyperglycaemia, insulin resistance, and relative insulin deficiency.[3 4] Both genetic and lifestyle factors will lead to T2DM, with obesity, low physical activity level, poor dietary practices, smoking habits and alcohol use being the primary risk factors for T2DM.[5-7]

Without proper treatment or management, T2DM will develop into serious complications and lead to potentially fatal conditions. In year 2012 alone, 1.5 million deaths worldwide were directly caused by diabetes.[8] There are also complications related to T2DM such as myocardial infarction, non-alcoholic fatty liver disease and diabetic nephropathy.[9 10] T2DM is widely regarded as an incurable but manageable condition through medications and lifestyle modifications. In management of T2DM through pharmacological approach, medications such as insulin injection, biguanides, thiazolidinedione, sulfonylureas, meglitinides and alpha-glucosidase inhibitors are used.[11]

The first line management for T2DM patients is lifestyle modification, specifically weight management for obese and overweight patients. The prevalence of obesity in patients with T2DM are high throughout the world. Over 30% of participants is reported with obesity in 38 of 44 studies pooled in a systematic review on observational studies for prevalence of obesity in T2DM patients. [12] Excess weight in T2DM patients can lead to higher risks for additional complications such as cardiovascular diseases. On the contrary, weight loss has led to an improved 24 hours plasma glucose profile, reduced HbA1c and increased insulin sensitivity. [13] American Diabetes Association also recommended maintaining >5% weight loss for patients with T2DM who are overweight or obese through diet, exercise and behavioral therapy. [14] This is supported by outcome in the DiRECT study has shown a clinically significant 46% remission to non-diabetic state among 306 participants who lost up to 15kg of weight. [15]

Dietary intervention is effective to achieve targeted weight and glycemic control in T2DM patients, [16] However, this approach can be challenging for patients and also healthcare providers as it requires compliance from the patients to follow the guidance provided to them. It might also be an effortful task for the patients as it requires a certain level of self-care knowledge and skills to prepare their own meals. The diabetes education given to the patients might be insufficient to help them develop self-efficacy skills for managing their diet. [17] Time limitation, family responsibilities and busy schedules may also hinder patients from preparing their own meals based on suggestions provided by dietitians. [17-19]

Meal Replacements (MR) are prepackaged food products or drinks that are designed to replace one or more meals and provide a defined amount of energy. [20] It is found out that portion-controlled MR is able to produce 31.5% more clinically significant weight loss (>5% weight loss one year) and significant BMI reduction in obese subjects as compared to standard food-based plan. [21] In the Look AHEAD study involving 5145 overweight or obese participants with T2DM, meal replacement as a part of intensive lifestyle intervention has reduced HbA1c significantly after one year intervention period. [22 23] Diet planning through meal replacement products is a useful approach for T2DM patients as they can be delivered easily to the community without much help from healthcare professionals. It has also proven to be a safe and effective method for increasing dietary compliance. [24] There are various MR trials and researches being carried out to date but not much is known on the thorough review of type, composition, dosage and delivery. These information is important as continuous quality improvement of MR and potential lead to better innovation.

With this scoping review we aim to collate literature on meal replacement for dietary management of T2DM patients. We will examine meal replacements available for Type 2 diabetes mellitus patients and their effects respectively on glucose control/HbA1C, weight reduction and other health status of the patients. The risks or side effects from the meal replacements will also be identified. The findings will be mapped by categorizing the papers and summarizing them. Specifically, the purposes of conducting this scoping review are:

i) To provide an overview of existing studies regarding usage of meal replacement on type-2 diabetic patients.

ii) To map out the outcomes of meal replacement on specific parameters of the participants.

iii) To map out the side effects of meal replacement among type-2 diabetic patients.

Aim

The aim of this manuscript is to present a protocol for a scoping review of meal replacements in managing Type 2 diabetes mellitus patients.

Methodology

The purpose of this scoping review is to gain an overview on meal replacements and its outcome in managing patients with T2DM. Scoping review is identical to systematic review but differs in purpose as scoping review aims to comprehensively map the evidences of a topic while systematic review seeks to summarize and analyze the most ideal topic on a specific question. [25]

The methods of this scoping review will be based on Arksey and O’Malley’s seminal framework for scoping reviews. [25] The approach to searching, screening and reporting of scoping review as suggested by Levac, Colqohoun and O’ Brien will be modified and utilized. [26] We will also use the Preferred Reporting Items for Systematic Review and Meta-Analysis Protocols (PRISMA-P) as a checklist for aspects applicable to scoping review. A completed PRISMA-P checklist is attached to this protocol (Additional file 1).

There are six stages involved in scoping review framework which included (1) identifying the research question, (2) identifying relevant studies, (3) selection of studies to be included, (4) charting of information and data from the studies, (5) collating, summarising and reporting the results and (6) conducting consultation with stakeholders and experts in diabetes

Stage 1: Identifying research questions

  1. What are the types, composition, dosage, delivery and duration of meal replacement plans available for managing T2DM patients?
  2. What are the outcomes of meal replacement on glycaemic control/HbA1C, weight reduction and other health status of T2DM patients?
  3. What are the side effects faced by T2DM patients taking meal replacements?

Stage 2: Identifying relevant studies

Identification of studies relevant to this review will be achieved by searching studies published between January 2000 to December 2019. The search will be conducted through several electronic databases (ie. Pubmed, Scopus, Cochrane Reviews, Google Scholar, Ebscohost, Science Direct). We will also search for grey literature (local non-indexed journals, websites and theses) regarding meal replacement in managing patients with type-2 diabetes mellitus published within the same period. The search for online databases will be filtered for humans’ and adults’ results. The results will be downloaded into EndNote and duplicate results will be removed.

Two independent reviewers (LC and AF) will be performing the search in parallel using a comprehensive search strategy. Search terms from key words, subject headings and synonyms such as meal replacement, type-II diabetes mellitus, glycemic control and weight reduction will be generated by the research team members in order to capture any potential resources from the databases. Table 1 outlines the initial keywords and search terms generated. Boolean operators (AND, OR, NOT) will be used to combine search terms within related keywords and is adapted to the syntax used by each database. If there are any search terms missing from the initial search terms, an additional search will be carried out using the updated search terms. Table 2 shows the search strings generated.

Table 1 List of keywords and synonyms generated as search terms

Meal Replacement

Type-2 Diabetes Mellitus

Glycaemic control

Weight reduction

Risks

Food Substitute

Diabetic

HbA1c

Weight Loss

Side effect

Alternative Serving

Diabetes 

Random Blood Sugar

Weight reduction

Danger

 

 

Diet Alternative

Non-insulin dependent Diabetes Mellitus

Glucose

Decrease in body weight

Hazardous

Alternative Nutrition

Diabetes Mellitus-onset

Fasting blood sugar

Body Weight Changes

Adverse effect

Diet Replacement

Type-II Diabetes Mellitus

2-Hour Post-Prandial Blood Glucose

BMI reduction

Bad

Diet plan Exchange

 

Glucose tolerance

Fatness

Negative effect

Replacement Drink

 

 

Adiposity

Harmful

Alternate nutrition

 

 

 

Detrimental 

Oral nourishing supplement

 

 

Antagonistic

Medicinal food

 

 

 

Unsafe




Table 2 List of search strings

Search string 1: 

 

“Meal Replacement*” OR “Food Substitute*” OR “Alternative Serving*” OR “Diet Alternative*” OR “Alternative Nutrition” OR “Diet Replacement*” OR “Diet plan Exchange” OR “Replacement Drink*” OR “Alternate nutrition” OR “Oral nourishing supplement*” OR “Medicinal food” AND “Type-2 Diabetes Mellitus” OR Diabetic OR Diabetes OR “Non-insulin dependent Diabetes Mellitus” OR “Diabetes Mellitus-onset” OR “Type-II Diabetes Mellitus”

 

Search string 2: 

 

“Meal Replacement*” OR “Food Substitute*” OR “Alternative Serving*” OR “Diet Alternative” OR “Alternative Nutrition” OR “Diet Replacement*” OR “Diet plan Exchange” OR “Replacement Drink*” OR “Alternate nutrition” OR “Oral nourishing supplement*” OR “Medicinal food” AND “Type-2 Diabetes Mellitus” OR Diabetic OR Diabetes OR “Non-insulin dependent Diabetes Mellitus” OR “Diabetes Mellitus-onset” OR “Type-II Diabetes Mellitus” AND “Glycaemic control” OR HbA1c OR “Random Blood Sugar” OR Glucose OR “Fasting blood sugar” OR “2-Hour Post-Prandial Blood Glucose” OR “Glucose tolerance”

 

Search string 3: 

 

“Meal Replacement*” OR “Food Substitute*” OR “Alternative Serving*” OR “Diet Alternative” OR “Alternative Nutrition” OR “Diet Replacement*” OR “Diet plan Exchange” OR “Replacement Drink*” OR “Alternate nutrition” OR “Oral nourishing supplement*” OR “Medicinal food” AND “Type-2 Diabetes Mellitus” OR Diabetic OR Diabetes OR “Non-insulin dependent Diabetes Mellitus” OR “Diabetes Mellitus-onset” OR “Type-II Diabetes Mellitus” AND “Weight reduction” OR “Weight Loss” OR “Weight reduction” OR “Decrease in body weight” OR “Body Weight Change*”

 

Search string 4:

“Meal Replacement*” OR “Food Substitute*” OR “Alternative Serving*” OR “Diet Alternative” OR “Alternative Nutrition” OR “Diet Replacement*” OR “Diet plan Exchange” OR “Replacement Drink*” OR “Alternate nutrition” OR “Oral nourishing supplement*” OR “Medicinal food” AND “Type-2 Diabetes Mellitus” OR Diabetic OR Diabetes OR “Non-insulin dependent Diabetes Mellitus” OR “Diabetes Mellitus-onset” OR “Type-II Diabetes Mellitus” AND “Risk*” OR “Side effect” OR “Dangerous” OR “Hazardous” OR “Adverse effect*” OR “Bad” OR “Negative effect*” OR “Harmful” OR “Detrimental” OR “Antagonistic” OR “Unsafe”

 

Stage 3: Selection of studies to be included

Inclusion criteria for the search will be studies ranging from January 2009 to April 2019 related to meal replacement with T2DM affected patients aged 18 and above (adult and elderly). These will include articles from primary studies, technical reports and review articles. Grey literatures (ie. Websites, local non-indexed journals and theses) will also be included. Language will be limited to English and Malay written materials only. Studies will be excluded if they include (1) type-1 diabetes mellitus patients, (2) pregnant women, (3) paediatric populations, (4) are not human studies and (5) meal replacements that are not self-administered.

Screening and selection of articles will be carried out in a three step process. In the first step, two researchers (LC and AF) will screen through all titles from the search results in databases and grey literatures using the search term generated from stage two previously. All articles involving meal replacements and T2DM patients will be considered.

In the second step, all researchers (LC, AF, SS, ZAM and NMT) will be working independently to screen through the selected titles and abstract obtained from step one for articles potentially related to the objectives. Researchers will meet up to compare the results and to resolve discrepancies. A diabetes professional will be consulted if the discrepancies cannot be resolved.

In the third step, similarly, all researchers (LC, AF, SS, ZAM and NMT) will be working independently to screen through the full article obtained from the second step. Efforts will be made to obtain the full papers through university library if full papers are not available online. The full articles will be studied through to ensure that they meet the objectives. Researchers will meet upon completion to compare results and resolve any discrepancies.

Articles which are irrelevant to the objectives will be excluded and results of relevant articles from the search will be managed by Endnote X5 programme and its extracted data will be recorded in Microsoft Excel. The entire process of reviewing will be guided by using the PRISMA-P (Preferred Reporting Items for Systematic Reviews and Meta-Analyses) flowchart. [27]

Stage 4: Charting of information and data from the studies

A data charting table (Additional file 2) is developed by the research team members to confirm relevance of studies screened and to extract findings from the studies. Findings will be extracted and categorized into table of evidences as below:

  1. Author(s)
  2. Publication year
  3. Objectives or purposes of the study
  4. Participants Characteristics
  5. Study Design
  6. Settings
  7. Meal Replacement type
  8. Dosage and Calorie
  9. Control Groups (if any)
  10. Duration
  11. Effect on HbA1c and glucose
  12. Effect on weight reduction
  13. Effect on other health status
  14. Side effects

Other additional findings which are not included in the category of charting table are listed under an extra column labelled as ‘notable findings’.

The main outcome of the data will be type and dosage of meal replacement and its effect on HbA1c, glucose and weight reduction. Additional outcome will be the side effects of the meal replacement.

The charting table will be discussed by all researchers in a meeting and pretested before implementation of 10 articles to ensure the table captures significant information correctly. Two researchers (LC and AF) will then work independently to extract and chart the data from articles that are screened previously. The other researchers (SS, ZAM, NMT) will check the extracted data for accuracy. Any disagreements will be discussed during group meetings.

Stage 5: Collating, summarizing and reporting of results

The literature will be mapped and arranged with the concepts mentioned previously. The results of the data extracted will be summarized and analysed. The general characteristics of included studies will be summarised. Descriptive statistics such as percentages or frequencies will be used to provide summary characteristics of the studies based on the type of meal replacement plan being used in the studies. The studies will be categorized based on their study design. Data will be presented using a table of findings based on the effects of the meal replacement on glycemic control parameters and weight reduction. Risks and side effects of meal replacement products on T2DM patients will also be discussed. Limitation and research gaps for the studies will also be discussed to provide better recommendations for future meal replacement studies.

Stage 6: Consultation with stakeholders

Consultation with stakeholders and experts are optional but recommended in a scoping review. The expert will be able to provide assistance on finding relevant articles and also give extra feedback on the results and data analysed. We will consult several experts in the diabetic field such as doctors and dieticians to provide additional insights in the data extracted. All input from the experts will be included in the review. 

Patient and Public Involvement

As this scoping review only involves literature-based studies, there is no patient or public involvement.

Discussion

The aim of this scoping review protocol is to provide a framework enabling us to review the research foci on meal replacement for the past 10 years. It will help us to map and summarize the findings from existing researches to identify limitations and provide recommendations for future research in nutrition intervention for diabetes. Although there have been several numbers of meal replacement studies carried out, there are no comprehensive evidences from these existing studies to provide us an overview on the current meal replacement scopes. It is anticipated that the result will be useful to a variety of stakeholders. The target audiences for the result will be those who are involved in diabetes and obesity healthcare sectors, including pharmaceutical industries, institutional decision makers and researchers. No ethics approval is required as this study only involves reviewing and extracting data from readily available publications and materials.

This review will be part of a research project in which the information obtained will be utilized in clinical trial of a developed meal replacement plan. The findings of this review will be summarized and written as an article for peer-reviewed publication. Our approaches to knowledge dissemination will also be done through presentations at T2DM and obesity related conferences such as Diabetes Asia Conference.

Abbreviations

T2DM

Type-2 diabetes mellitus

MR

Meal Replacement

Declarations

Ethics approval and consent to participate

Not applicable. No ethics are required as this study only involves reviewing and extracting data from readily available materials.

Consent for publication

All authors have consented for publication.

Availability of data and materials

The datasets used and/or analysed during the current study are available from the corresponding author on reasonable request.

Competing interests

The authors declare that they have no competing interests.

Funding

The authors received no specific funding for this work.

Authors' contributions

LC, AF, SS, ZAM and NMT conceptualised the study. LC prepared the draft proposal under supervision of AF. LC, AF, SS, ZAM and NMT contributed to background literature and developed the study design. LC, AF, SS, ZAM and NMT shaped the search strategy and carried out database screening. LC and AF proposed the data extraction strategy. LC drafted the protocol manuscript. LC, AF, SS, ZAM and NMT edited the protocol manuscript. All authors read and approved the final manuscript.

Acknowledgements

The authors would like to thank the National University of Malaysia (UKM) for the provision of resources towards this review and the Centre for Healthy Ageing and Wellness (H-CARE) UKM for training and technical support.

Open Access

This article is distributed under the terms of the Creative Commons Attribution 4.0 International License (http://creativecommons.org/licenses/by/4.0/), which permits unrestricted use, distribution, and reproduction in any medium, provided you give appropriate credit to the original author(s) and the source, provide a link to the Creative Commons license, and indicate if changes were made. The Creative Commons Public Domain Dedication waiver (http://creativecommons.org/publicdomain/zero/1.0/) applies to the data made available in this article, unless otherwise stated.

Additional Files

Additional File 1: PRISMA-P 2015 Checklist.

Additional File 2: Data extraction form.

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