This secondary analysis of another randomized controlled trial ^[3] assessed whether changes in dietary patterns affected HbA1C independently of body weight changes in participants recently diagnosed with T2D.

In the original study, the authors randomized 593 adults in England to one of three groups for 12 months:

Usual care (C): The participants received standard dietary and exercise advice after randomization and at the end of the study.
Diet intervention (DIET): The diet intervention was designed to produce a 5–10% reduction in body weight that was maintained throughout the study. A registered dietitian taught the participants how many portions of each food group to consume based on the Diabetes U.K. dietary guidelines. The participants were encouraged to choose foods low in calories, fat, and glycemic index. The participants also met with the study dietitian at baseline and 3, 6, 9, and 12 months, and study nurses met with the participants every 6 weeks to reinforce dietary advice and goal setting.
Diet and physical activity intervention (DIET + PA): The participants in this group received the same dietary intervention as those in the DIET group. Additionally, they performed at least 30 minutes of brisk walking at least 5 days per week in addition to their current levels of physical activity.

All the participants had been diagnosed with T2D 5–8 months prior to the study, were 30–80 years old, had an HbA1C of no more than 10%, LDL-C of no more than 155 mg/dL, blood pressure of no more than 180/100 mmHg, a BMI of at least 25 kg/m², and weighed less than 400 lbs.

During the first six months, diabetes medications were only changed if fasting blood glucose rose to more than 216 mg/dL, participants became symptomatic, or blood pressure was higher than 160/90 mm Hg at any study visit. During the second 6 months, the participants were treated as appropriate to maintain HbA1C of less than 7.4%, blood pressure of less than 140/85 mm Hg, total cholesterol of less than 155 mg/dL, HDL-C of less than 39 mg/dL, LDL-C of less than 77 mg/dL, and triglycerides of less than 177 mg/dL.

The participants self-reported dietary data via 4-day food diaries (two weekdays and two weekend days) at baseline, 6, and 12 months. From the 4-day food diaries, the authors identified two dietary patterns at baseline associated with changes in HbA1C using reduced rank regression (a statistical technique that can identify patterns predictive of health outcomes in reported dietary intake).

Carb/Fat Balance dietary pattern (carb/fat): Higher pattern scores correlated with a higher percentage of energy intake from starches and sugars, a higher fiber density (grams of fiber/total kcal consumed), and a lower percentage of energy from saturated fats, monounsaturated fats, and polyunsaturated fats. A higher carb/fat pattern was associated with eating more fresh fruits, low-fat milk, boiled/baked potatoes, and legumes while eating less higher-fat/processed meat, butter/animal fat, red meat, and low-fiber bread.
Obesogenic dietary pattern (Ob): Higher pattern scores correlated with a higher dietary energy density (total kcal consumed/food weight in grams), a higher percentage of energy from fat, and a lower fiber density. A higher Ob diet pattern was associated with eating more low-fiber bread, processed meat, coated chicken/fish, and fried/roasted potatoes/chips while eating less fresh fruit, raw/boiled/grilled vegetables, yogurt, and boiled/baked potatoes.

The primary outcome was the change in HbA1C over 0–6 months. The secondary outcomes were changes in HbA1C over 6–12 months and 0–12 months.

Low-Glycemic-Index Foods

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