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Abstract
Background
Type 2 diabetes mellitus (T2DM) represents a global public health crisis affecting over 537 million adults worldwide, with fasting blood glucose (FBG) serving as a critical diagnostic and monitoring parameter. Medical nutrition therapy (MNT), particularly when delivered by registered dietitians, has emerged as a cornerstone of diabetes management, yet the specific relationship between dietitian-guided MNT and FBG outcomes requires comprehensive synthesis. This review systematically examines the association between dietitian-guided medical nutrition therapy and fasting blood glucose control in adults with type 2 diabetes, evaluating intervention characteristics, dietary approaches, dose-response relationships, and outcomes across diverse populations. A comprehensive literature search was conducted across multiple databases including PubMed, SciSpace, and Google Scholar using terms related to dietitian-guided MNT, fasting blood glucose, glycemic control, and type 2 diabetes in adults. Studies were included if they involved adult populations with T2DM, dietitian-delivered or dietitian-supervised nutrition interventions, and reported FBG and/or HbA1c outcomes. Data were extracted on study design, population characteristics, intervention details, dietary approaches, consultation frequency, and glycemic outcomes. Evidence from 60 studies demonstrates that dietitian-guided MNT consistently improves fasting blood glucose and HbA1c in adults with T2DM. Reductions in FBG ranged from 13.4 to 28 mg/dL, with HbA1c improvements of 0.4% to 2.09% depending on baseline glycemic control, intervention intensity, and duration. Effective interventions typically involved 3-6 dietitian consultations over 3-12 months, with individualized dietary approaches including carbohydrate counting, low-glycemic index diets, Mediterranean diet patterns, caloric restriction, and macronutrient modification. Greater improvements were observed in patients with poorly controlled baseline glucose (HbA1c ≥7%), newly diagnosed diabetes, and those receiving more intensive dietitian contact. Key dietary mechanisms included carbohydrate intake reduction (associated with 0.7% HbA1c improvement), energy restriction (229-500 kcal/day deficit), and adoption of low-GI foods. Barriers included socioeconomic factors, cultural dietary patterns, and healthcare access limitations.
Dietitian-guided medical nutrition therapy demonstrates robust, clinically significant associations with improved fasting blood glucose and overall glycemic control in adults with type 2 diabetes. The evidence supports MNT as a first-line intervention, with dose-response relationships favoring more intensive, individualized, and sustained dietitian contact. Integration of dietitian-led MNT into standard diabetes care, with attention to cultural adaptation and accessibility, represents a critical strategy for optimizing metabolic outcomes and reducing diabetes-related complications.