Volume 20, Issue 4 p. 858-871
ORIGINAL ARTICLE

Effects of an energy-restricted low-carbohydrate, high unsaturated fat/low saturated fat diet versus a high-carbohydrate, low-fat diet in type 2 diabetes: A 2-year randomized clinical trial

Jeannie Tay PhD

Jeannie Tay PhD

Commonwealth Scientific and Industrial Research Organisation (CSIRO) – Health and Biosecurity, Adelaide, Australia

Discipline of Medicine, University of Adelaide, Adelaide, Australia

Agency for Science, Technology and Research (A-STAR), Singapore

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Campbell H. Thompson MD

Campbell H. Thompson MD

Discipline of Medicine, University of Adelaide, Adelaide, Australia

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Natalie D. Luscombe-Marsh PhD

Natalie D. Luscombe-Marsh PhD

Commonwealth Scientific and Industrial Research Organisation (CSIRO) – Health and Biosecurity, Adelaide, Australia

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Thomas P. Wycherley PhD

Thomas P. Wycherley PhD

Alliance for Research in Exercise, Nutrition and Activity (ARENA), Sansom Institute for Health Research, University of South Australia, Adelaide, Australia

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Manny Noakes PhD

Manny Noakes PhD

Commonwealth Scientific and Industrial Research Organisation (CSIRO) – Health and Biosecurity, Adelaide, Australia

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Jonathan D. Buckley PhD

Jonathan D. Buckley PhD

Alliance for Research in Exercise, Nutrition and Activity (ARENA), Sansom Institute for Health Research, University of South Australia, Adelaide, Australia

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Gary A. Wittert MD

Gary A. Wittert MD

Discipline of Medicine, University of Adelaide, Adelaide, Australia

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William S. Yancy Jr MD

William S. Yancy Jr MD

Division of General Internal Medicine, Department of Medicine, Duke University Medical Center, Durham, North Carolina

Center for Health Services Research in Primary Care, Veterans Affairs Medical Center, Durham, North Carolina

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Grant D. Brinkworth PhD

Corresponding Author

Grant D. Brinkworth PhD

Commonwealth Scientific and Industrial Research Organisation (CSIRO) – Health and Biosecurity, Adelaide, Australia

Correspondence

Grant Brinkworth, PhD, Commonwealth Scientific and Industrial Research Organisation- Health and Biosecurity, Riverside Corporate Park, 11 Julius Avenue, North Ryde, NSW, Australia, 2113. Email: grant.brinkworth@csiro.au

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First published: 27 November 2017
Citations: 137
Funding information This study was supported by a National Health and Medical Research Council of Australia Project Grant (103415). J. T. was supported by a postgraduate research scholarship from the Agency for Science, Technology and Research (A-STAR), Singapore. Funding sponsors had no role in the design, conduct or reporting of the study or the decision to submit the manuscript for publication.

Abstract

Aim

To examine whether a low-carbohydrate, high-unsaturated/low-saturated fat diet (LC) improves glycaemic control and cardiovascular disease (CVD) risk factors in overweight and obese patients with type 2 diabetes (T2D).

Methods

A total of 115 adults with T2D (mean [SD]; BMI, 34.6 [4.3] kg/m2; age, 58 [7] years; HbA1c, 7.3 [1.1]%) were randomized to 1 of 2 planned energy-matched, hypocaloric diets combined with aerobic/resistance exercise (1 hour, 3 days/week) for 2 years: LC: 14% energy as carbohydrate, 28% as protein, 58% as fat (<10% saturated fat); or low-fat, high-carbohydrate, low-glycaemic index diet (HC): 53% as CHO, 17% as protein, 30% as fat (<10% saturated fat). HbA1c, glycaemic variability (GV), anti-glycaemic medication effect score (MES, calculated based on the potency and dosage of diabetes medication), weight, body composition, CVD and renal risk markers were assessed before and after intervention.

Results

A total of 61 (LC = 33, HC = 28) participants completed the study (trial registration: http://www.anzctr.org.au/, ANZCTR No. ACTRN12612000369820). Reductions in weight (estimated marginal mean [95% CI]; LC, −6.8 [−8.8,−4.7], HC, −6.6 [−8.8, −4.5] kg), body fat (LC, −4.3 [−6.2, −2.4], HC, −4.6 [−6.6, −2.7] kg), blood pressure (LC, −2.0 [−5.9, 1.8]/ −1.2 [−3.6, 1.2], HC, −3.2 [−7.3, 0.9]/ −2.0 [−4.5, 0.5] mmHg), HbA1c (LC, −0.6 [−0.9, −0.3], HC, −0.9 [−1.2, −0.5] %) and fasting glucose (LC, 0.3 [−0.4, 1.0], HC, −0.4 [−1.1, 0.4] mmol/L) were similar between groups (P ≥ 0.09). Compared to HC, the LC achieved greater reductions in diabetes medication use (MES; LC, −0.5 [−0.6, −0.3], HC, −0.2 [−0.4, −0.02] units; P = 0.03), GV (Continuous Overall Net Glycemic Action calculated every 1 hour (LC, −0.4 [−0.6, −0.3], HC, −0.1 [−0.1, 0.2] mmol/L; P = 0.001), and 4 hours (LC, −0.9 [−1.3, −0.6], HC, −0.2 [−0.6, 0.1] mmol/L; P = 0.02)); triglycerides (LC, −0.1 [−0.3, 0.2], HC, 0.1 [−0.2, 0.3] mmol/L; P = 0.001), and maintained HDL-C levels (LC, 0.02 [−0.05, 0.1], HC, −0.1 [−0.1, 0.01] mmol/L; P = 0.004), but had similar changes in LDL-C (LC, 0.2 [−0.1, 0.5], HC, 0.1 [−0.2, 0.4] mmol/L; P = 0.85), brachial artery flow mediated dilatation (LC, −0.5 [−1.5, 0.5], HC, −0.4 [−1.4, 0.7] %; P = 0.73), eGFR and albuminuria.

Conclusions

Both diets achieved comparable weight loss and HbA1c reductions. The LC sustained greater reductions in diabetes medication requirements, and in improvements in diurnal blood glucose stability and blood lipid profile, with no adverse renal effects, suggesting greater optimization of T2D management.