The effectiveness of medical nutrition therapy provided by a dietitian in adults with prediabetes: a systematic review and meta-analysis

BACKGROUND

A total of 374 million adults worldwide are living with prediabetes, 70% of whom will develop type 2 diabetes mellitus (T2DM) in their lifetime. Medical nutrition therapy (MNT) provided by a dietitian, such as that found in lifestyle interventions, has the potential to improve glycemic control and prevent progression to T2DM.

OBJECTIVES

The objective of this systematic review was to examine the effectiveness of MNT provided by a dietitian, compared with standard care, on glycemic, cardiometabolic, and anthropometric outcomes in adults with prediabetes.

METHODS

Searches were conducted for randomized controlled trials (RCTs) published between 1995 and 2022 using electronic databases MEDLINE, CINHAL, and Cochrane Central. The risk of bias was assessed using version 2 of the Cochrane risk-of-bias tool for RCTs. Meta-analyses were conducted using a random-effects model. The certainty of evidence was assessed for each outcome using the Grading of Recommendations, Assessment, Development and Evaluation (GRADE) method, and a summary of findings table was created using the GRADEpro Guideline Development Tool.

RESULTS

Thirteen RCTs were included in the analysis, showcasing a variety of MNT interventions delivered by dietitians. Intervention durations ranged from 3 to 24 mo. Compared with standard care, MNT improved hemoglobin A1c (HbA1c) (mean difference [95% confidence interval]: -0.30% [-0.49, -0.12]) and fasting blood glucose (FBG) (-4.97 mg/dL [-6.24, -3.71]). Statistically significant improvements were found in anthropometrics (weight, body mass index, and waist circumference), cholesterol (total, high-, and low-density lipoproteins), and blood pressure (systolic and diastolic). No significant effect was found on T2DM or triglycerides. The certainty of evidence was moderate for FBG and low for HbA1c and incidence of T2DM.

CONCLUSIONS

In adults with prediabetes, MNT was effective in improving glycemic outcomes, anthropometrics, blood pressure, and most lipid levels. However, most studies had a risk of bias because of the randomization process or deviations from intended interventions. MNT plays a key role in improving cardiometabolic risk factors in adults with prediabetes.

TRIAL REGISTRATION NUMBER

This study was registered with the registration ID #351421, available from https://www.crd.york.ac.uk/prospero/display_record.php?RecordID=351421.

Factors Beyond Carbohydrate to Consider When Determining Meantime Insulin Doses: Protein, Fat, Timing, and Technology

For many years, carbohydrate counting has been a popular strategy for determining mealtime insulin doses for people with diabetes who are on a multiple daily injection regimen or continuous subcutaneous insulin infusion. This approach assumes that only carbohydrate-containing foods and beverages affect postprandial glucose levels. However, many studies have indicated that the fat and protein content of a meal can play an important role in delaying postprandial hyperglycemia and should be considered when trying to optimize postprandial glucose levels. This article reviews research on making insulin dose adjustments for high-fat and high-protein meals, as well as the timing of mealtime insulin doses.

Why Weight Loss Maintenance Is Difficult

IN BRIEF This article reviews studies related to biological mechanisms that make weight loss maintenance difficult. Approximately 50% of weight variance is reported to be determined by genetics and 50% by the environment (energy-dense foods and reduced physical activity). Body weight is tightly regulated by hormonal, metabolic, and neural factors. Hormonal adaptations (decreases in leptin, peptide YY, cholecystokinin, and insulin and increases in ghrelin, glucagon-like peptide 1, gastric inhibitory polypeptide, and pancreatic polypeptide) encourage weight gain after diet-induced weight loss and continue for at least 1 year after initial weight reduction. Weight loss also results in adaptive thermogenesis (decreased resting metabolic rate), which is also maintained long-term. Neural factors such as dopamine also signal the need to respond to an increased desire for fatty foods after weight loss.

Enhancing Access to Diabetes Self-management Education in Primary Care

Purpose

The purpose of this continuous quality improvement project was to improve access to diabetes self-management education (DSME) and to evaluate the impact on glycemic and weight control by translating an academic medical center’s DSME program, accredited per the Education Recognition Program (ERP) of the American Diabetes Association, into a program offered at primary care clinics (PCCs).

Methods

Certified diabetes educators from the medical center trained PCC registered dietitian nutritionists, registered nurses, and social workers to provide DSME in their community-based clinic. Main outcomes of this retrospective, pretest/posttest, observational project were to evaluate enrollment in DSME classes and change in A1C and weight as patients underwent a combined intervention of diabetes education classes with or without consultation and support from a PCC registered dietitian nutritionist or registered nurse.

Results

PCC DSME was associated with increased enrollment in DSME classes and a significant reduction of A1C and weight at 3 and 6 months post-DSME. Greatest A1C and weight reductions were observed in patients with newly diagnosed diabetes. Reductions were also seen in patients with diabetes duration ≥10 years, participants taking insulin, and those with depression.

Conclusions

PCC DSME availability increased access to group diabetes education and resulted in reduced A1C and weight for participants. This model was successful in translating an established academic accredited DSME-ERP into a PCC. Results have implications for increasing access to diabetes education programs and improving diabetes control for patients not located near major hospital-based DSME programs.

Improving Patient Experience With Insulin Infusion Sets

Purpose

Insulin infusion sets (IISs) are an essential component of safe and effective insulin pump therapy. Establishing best practices for their use has been impeded by a lack of formal study and limited resources for clinician and patient education. Recent innovations in IIS science promise to change this status quo by increasing awareness of such problems as unexplained hyperglycemia and infusion set occlusion.

Methods

In August 2015, a panel of diabetologists and certified diabetes educators from various disciplines was convened to reconsider IIS-related complications of pump therapy, to better characterize infusion set factors affecting patient experience, and to update priorities for optimizing current technologies. Actionable guidelines were provided for addressing common issues, including skin reactions, site rotation and set changes, dislodgment of the infusion set, and partial or complete blockage of the catheter. These issues may underlie episodes of IIS failure and/or unexplained hyperglycemia.

Conclusion

Development of practical tools and standardized guidelines for empowering patients to prevent, diagnose, and troubleshoot IIS problems that contribute to unexplained hyperglycemia will be necessary to realize the full benefit of insulin pump therapy along the continuum of diabetes education.

Lifestyle intervention: nutrition therapy and physical activity

Diabetes now affects more than 29 million Americans, and more than 9 million of these people do not know they have diabetes. In adults, type 2 diabetes accounts for about 90% to 95% of all diagnosed cases of diabetes and is the focus of this article. Lifestyle intervention is part of the initial treatment as well as the ongoing management of type 2 diabetes. Lifestyle intervention encompasses a healthful eating plan, physical activity, and often medication to assist in achievement of glucose, lipid, and blood pressure goals. Patient education and self-care practices are also important aspects of disease management.

Evidence-based diabetes nutrition therapy recommendations are effective: the key is individualization

Current nutrition therapy recommendations for the prevention and treatment of diabetes are based on a systematic review of evidence and answer important nutrition care questions. First, is diabetes nutrition therapy effective? Clinical trials as well as systematic and Cochrane reviews report a ~1%-2% lowering of hemoglobin A1c values as well as other beneficial outcomes from nutrition therapy interventions, depending on the type and duration of diabetes and level of glycemic control. Clinical trials also provide evidence for the effectiveness of nutrition therapy in the prevention of diabetes. Second, are weight loss interventions important and when are they beneficial? Modest weight loss is important for the prevention of type 2 diabetes and early in the disease process. However, as diabetes progresses, weight loss may or may not result in beneficial glycemic and cardiovascular outcomes. Third, are there ideal percentages of macronutrients and eating patterns that apply to all persons with diabetes? There is no ideal percentage of macronutrients and a variety of eating patterns has been shown to be effective for persons with diabetes. Treatment goals, personal preferences (eg, tradition, culture, religion, health beliefs, economics), and the individual's ability and willingness to make lifestyle changes must all be considered by clinicians and/or educators when counseling and educating individuals with diabetes. A healthy eating pattern emphasizing nutrient-dense foods in appropriate portion sizes, regular physical activity, and support are priorities for all individuals with diabetes. Reduced energy intake for persons with prediabetes or type 2 diabetes as well as matching insulin to planned carbohydrate intake are intervention to be considered. Fourth, is the question of how to implement nutrition therapy interventions in clinical practice. This requires nutrition care strategies.

Nutrition therapy recommendations for the management of adults with diabetes

There is no standard meal plan or eating pattern that works universally for all people with diabetes. In order to be effective, nutrition therapy should be individualized for each patient/client based on his or her individual health goals; personal and cultural preferences; health literacy and numeracy; access to healthful choices; and readiness, willingness, and ability to change. Nutrition interventions should emphasize a variety of minimally processed nutrient dense foods in appropriate portion sizes as part of a healthful eating pattern and provide the individual with diabetes with practical tools for day-to-day food plan and behavior change that can be maintained over the long term.