Creating a paradigm shift for diabetes dietary management

Grant D Brinkworth, Campbell H Thompso

Very low and higher carbohydrate diets promote differential appetite responses in adults with type 2 diabetes: a randomized trial

Background: Effects of very low carbohydrate (VLC) diets on appetite response in individuals with type 2 diabetes remain unclear. Objective: A secondary analysis was conducted to determine appetite responses to an energy-restricted [30% of energy (%E) deficit] very low carbohydrate (VLC) diet compared with a higher carbohydrate (HC) diet in adults who were overweight or obese with type 2 diabetes. Methods: Forty-four men and 40 women (mean ± SD, age: 58.7 ± 6.6 y; weight: 100.4 ± 15.5 kg; BMI: 34.5 ± 4.1 kg/m2; glycated hemoglobin: 7.3 ± 1.0%; duration of diabetes: 6.7 ± 5.6 y) were randomly assigned to diets categorized as VLC [14%E carbohydrate (<50 g/d), 28%E protein, 58%E fat (<10%E saturated fat)], or energy-matched HC [53%E carbohydrate, 17%E protein, 30%E fat (<10%E saturated fat)] combined with progressive multicomponent exercise (60 min; 3 d/wk). Body weight, average weekly "daily fasting" and "daily overall" appetite perceptions (hunger, fullness, prospective consumption, and desire to eat-visual analog scales) were assessed at baseline and after 4 and 16 wk. Changes between diets over time were assessed using repeated measures ANOVA. Results: Significant decreases in body weight did not differ between groups (VLC: -11.0 ± 5.4 kg/16 wk compared with HC: -10.1 ± 4.3 kg/16 wk, P = 0.40). There was no difference between diet groups in "daily fasting" appetite ratings (P ≥ 0.30) or "daily overall" hunger and desire to eat (P ≥ 0.21). Compared with HC, VLC had greater decreases in "daily overall" ratings of fullness at Week 4 (VLC: -6 ± 2 compared with HC: 1 ± 2 arbitrary units, P = 0.001) and Week 16 (VLC: -3 ± 1 compared with HC: 3 ± 2 arbitrary units, P = 0.019) and reduced prospective consumption ratings at Week 4 (VLC: 5 ± 1 compared with HC: 0 ± 1 arbitrary units, P = 0.008). Conclusions: In the context of energy restriction, both HC and VLC energy-matched diets promoted comparable effects on fasting perceptions of appetite, but the HC diet resulted in greater "daily overall" fullness and reduced prospective consumption. Further research is required to evaluate the effects of ad libitum diets differing in amounts of carbohydrate on appetite response in populations with type 2 diabetes.Noor A Struik, Grant D Brinkworth, Campbell H Thompson, Jonathan D Buckley, Gary Wittert, and Natalie D Luscombe-Mars

Nutritional adequacy of very low- and high-carbohydrate, low saturated fat diets in adults with type 2 diabetes: a secondary analysis of a 2-year randomised controlled trial

Background: Growing evidence supports use of very low-carbohydrate (LC) diets for glycaemic control in type 2 diabetes. However, limited data on the micronutrient adequacy of LC diets exist. Objective: This study compared the long-term effects of a very low-carbohydrate, high unsaturated/low saturated fat (LC) diet to a high-carbohydrate, low-fat (HC) diet on micronutrient biomarkers in adults with obesity and type 2 diabetes. Methods: 115 adults with type 2 diabetes (mean[SD]; BMI:34.6[4.3]kg/m², age:58[7]yrs, HbA1c:7.3[1.1]%, 56[12]mmol/mol) were randomized to one of two planned, nutritionally-replete, energy-matched, hypocaloric diets (500-1000kcal/day deficit): (1) LC:14% energy carbohydrate, 28%protein, 58%fat[<10% saturated fat]) or (2) HC:53%carbohydrate, 17%protein, 30%fat [<10%saturated fat]) for 2 years. Nutritional biomarkers- folate, β-carotene, vitamin B12, D, E, copper, zinc, selenium, calcium, magnesium, sodium, potassium, iron, ferritin, transferrin and transferrin saturation were measured in fasting blood at baseline, 24, 52 and 104 weeks. Results: 61 participants completed the study with similar dropouts in each group (P=0.40). For all biomarkers assessed, there were no differential response between groups overtime (P≥0.17 time x diet interaction). Mean vitamin and mineral levels remained within normal (laboratory-specific) reference ranges without any reported cases of clinical deficiencies. Conclusion: In free-living individuals with type 2 diabetes, nutrition biomarkers within normal ranges at baseline did not change significantly after 2 years on a prescribed LC or HC diet. These results demonstrate the feasibility of delivering a nutritionally replete LC diet and the importance of considering nutritional factors in planning LC diets that have strong public health relevance to the dietary management of type 2 diabetes.Jeannie Tay, Campbell H. Thompson, Natalie D. Luscombe-Marsh, Manny Noakes, Jonathan D. Buckley, Gary A. Wittert, Grant D. Brinkwort

Effects of almond consumption on metabolic function and liver fat in overweight and obese adults with elevated fasting blood glucose: a randomised controlled trial

Abstract not availableJane Bowen, Natalie D. Luscombe-Marsh, Welma Stonehouse, Cuong Tran, Geraint B. Rogers, Nathan Johnson, Campbell H. Thompson, Grant D. Brinkwort