Impact of a Low-Carbohydrate Compared with Low-Fat Breakfast on Blood Glucose Control in Type 2 Diabetes: A Randomized Trial

Barbara F Oliveira; Courtney R Chang; Kate Oetsch; Kaja Falkenhain; Kara Crampton; Matthew Stork; Malvinder Hoonjan; Thomas Elliott; Monique E Francois; Jonathan P Little

doi:10.1016/j.ajcnut.2023.04.032

Impact of a Low-Carbohydrate Compared with Low-Fat Breakfast on Blood Glucose Control in Type 2 Diabetes: A Randomized Trial

Am J Clin Nutr. 2023 Jul;118(1):209-217. doi: 10.1016/j.ajcnut.2023.04.032. Epub 2023 May 29.

Affiliations

¹ School of Health and Exercise Sciences, University of British Columbia, Kelowna, British Columbia, Canada.
² School of Medical, Indigenous and Health and Sciences, University of Wollongong, Wollongong, New South Wales, Australia; Illawarra Health and Medical Research Institute, Wollongong, New South Wales, Australia.
³ Ophtamology, Okanagan Retina, Kelowna, British Columbia, Canada.
⁴ Division of Endocrinology, Department of Medicine, University of British Columbia, Vancouver, British Columbia, Canada.
⁵ School of Health and Exercise Sciences, University of British Columbia, Kelowna, British Columbia, Canada. Electronic address: jonathan.little@ubc.ca.

PMID: 37257563
DOI: 10.1016/j.ajcnut.2023.04.032

Abstract

Background: In type 2 diabetes (T2D), consuming carbohydrates results in a rapid and large increase in blood glucose, particularly in the morning when glucose intolerance is highest.

Objectives: We investigated if a low-carbohydrate (LC) breakfast (∼465 kcal: 25 g protein, 8 g carbohydrates, and 37 g fat) could improve glucose control in people with T2D when compared with a low-fat control (CTL) breakfast (∼450 kcal:20 g protein, 56 g carbohydrates, and 15 g fat).

Methods: Participants with T2D (N = 121, 53% women, mean age 64 y) completed a remote 3-month parallel-group randomized controlled trial comparing a LC with standard low-fat guideline CTL breakfast. The change in HbA1c was the prespecified primary outcome. Continuous glucose monitoring, self-reported anthropometrics, and dietary information were collected for an intention-to-treat analysis.

Results: HbA1c was reduced (-0.3%; 95% CI: -0.4%, -0.1%) after 12 wks of a LC breakfast, but the between-group difference in HbA1c was of borderline statistical significance (-0.2; 95% CI: -0.4, 0.0; P = 0.06). Self-reported total daily energy (-242 kcal; 95% CI: -460, -24 kcal; P = 0.03) and carbohydrate (-73 g; 95% CI: -101, -44 g; P < 0.01) intake were lower in the LC group but the significance of this difference is unclear. Mean and maximum glucose, area under the curve, glycemic variability, standard deviation, and time above range were all significantly lower, and time in the range was significantly higher, in the LC group compared with CTL (all P < 0.05).

Conclusions: Advice and guidance to consume a LC breakfast appears to be a simple dietary strategy to reduce overall energy and carbohydrate intake and improve several continuous glucose monitoring variables when compared with a CTL breakfast in persons living with T2D. The trial was registered at clinicaltrials.gov as NCT04550468.

Keywords: breakfast; chronobiology; glycemic control; low-carbohydrate diets; nutrition; type 2 diabetes.

Publication types

Randomized Controlled Trial
Research Support, Non-U.S. Gov't

MeSH terms

Blood Glucose Self-Monitoring
Blood Glucose* / metabolism
Breakfast
Diabetes Mellitus, Type 2*
Diet, Fat-Restricted
Dietary Carbohydrates / metabolism
Female
Glucose
Glycated Hemoglobin
Glycemic Control
Humans
Male
Middle Aged

Substances

Blood Glucose
Glycated Hemoglobin
Dietary Carbohydrates
Glucose

Associated data

ClinicalTrials.gov/NCT04550468