Date of Award


Document Type


Degree Name

Doctor of Medical Science (DMSc)


Department of Physician Assistant Medicine

First Advisor

Andrea Abernathy

Second Advisor

Tim Alyward, MPAS, PA-C

Third Advisor

Justin M. Gambini, DMSc, MSAPS, PA-C, DFAAPA


Purpose: The purpose of this review is to explore whether plant-based (vegan) diets result in greater reductions in hemoglobin A1c (HbA1c) than high-fat carbohydrate-restricted (ketogenic) diets in adults with type 2 diabetes mellitus.

Search Criteria: PubMed and Cochrane library databases were systematically searched for all relevant studies using MeSH terms (("diet, high fat" AND "diet, carbohydrate restricted") OR "diet, ketogenic" OR "diet, vegan") AND "diabetes mellitus, type 2/therapy". Limiting the research to meta-analyses and systematic reviews narrowed the results to six articles. One systematic review was excluded because it examined the effects of ketogenic diets on the quality of life of adults with chronic disease, not specifically glycemic control in patients with type 2 diabetes mellitus.

Results: Eight randomized controlled trials reported a reduction of HbA1c between 0.3-1.4% after a vegan diet, but only two of the eight studies showed a statistically significant mean difference between the intervention and control groups. In a separate review, eight of thirteen studies showed a reduction of HbA1c ranging from 0.6-3.3% with a mean reduction of 1.07% following a ketogenic diet but offered no controls for comparison. A meta73 analysis of fourteen trials revealed that a ketogenic diet provided an average of 0.5% greater reduction in HbA1c compared to control (primarily low-fat) diets. The last two reviews agreed that vegan diets appear promising, but one included the benefits of ketogenic diets while the other found the studies on ketogenic diets inconclusive. Conclusion: While the results of some of the selected studies appear promising, the consensus among the systematic review and meta-analyses is that further research is needed to determine which eating patterns are most effective for improving glycemic control in type 2 diabetes.

McCune_A_DMSc_734_Symposium_Poster.pdf (435 kB)
Poster presented at research symposium