We evaluated decreases in glycosylated hemoglobin (HbA1c) achieved by reducing carbohydrate from various sources in type 2 diabetes mellitus patients.

We followed up 138 male and 107 female outpatients on a moderate low-carbohydrate diet without diabetic medication for 6 months. Changes in carbohydrate sources (Δcarbohydrate) were assessed from 3-day dietary records at baseline and 6 months, and associations with changes in HbA1c (ΔHbA1c) were examined with Spearman's correlation coefficients (r_s) and multiple regression analysis.

ΔHbA1c was −1.5%±1.6% in men and −0.9%±1.3% in women, while Δtotal carbohydrate was −115.3±103.7 g/day in men and −63.6±71.1 g/day in women. Positive associations with ΔHbA1c were found for Δtotal carbohydrate (r_s=0.584), Δcarbohydrate from soft drinks (0.368), confectionery (0.361), rice (0.325), bread (0.221), Chinese soup noodles (0.199) in men, and Δtotal carbohydrate (0.547) and Δcarbohydrate from rice (0.376) and confectionery (0.195) in women. Reducing carbohydrate sources by 50 g achieved decreases in HbA1c of 0.43% for total carbohydrate, 1.33% for soft drinks, 0.88% for confectionery, 0.63% for bread, 0.82% for Chinese soup noodles and 0.34% for rice in men and 0.45% for total carbohydrate, 0.67% for confectionery and 0.34% for rice in women, although mean reductions in carbohydrate from these sources were much smaller than that from rice.

Decreases in HbA1c achieved by reducing carbohydrate from soft drinks, confectionery, bread and Chinese soup noodles were 2- to 4-fold greater than that for rice. Our results will enable patients to decrease HbA1c efficiently (UMIN000009866).

Koreans eat rice, which is usually served in a rice bowl. We investigated the effect of a meal plan using small rice bowls on the total energy intake (TEI) and the marcronutrient intake in Korean men with type 2 diabetes.

A total of 62 men with type 2 diabetes were divided by body mass index (BMI) (normal weight [NW], BMI<23 kg/m²; overweight [OW], 23≤BMI<25 kg/m²; obese [OB], BMI≥25 kg/m²) and proportions of carbohydrate intake to TEI (PCI) (low carbohydrate intake [LC], <55%; recommended carbohydrate intake [RC], ≥55% and ≤60%; high carbohydrate intake [HC], >60%). The 3-day dietary records were analyzed for TEI and proportions of macronutrients, before and 2 weeks after a small-sized (300 mL) rice bowl based education was given.

There were no significant differences in the age and BMI within the sub-groups by BMI and PCI groups. In baseline, the ratio of TEI to recommended total energy intake (RTR) of OW and OB were higher than that of NW. The PCI of HC was higher than that of LC and alcohol intake of HC was lower than that of LC. After education, the reduction of RTREI in OB was higher than that in OW and NW. The reduction of PCI in HC was higher than that of LC.

A small rice bowl based meal plan was effective for the reduction of energy intake and control of marcronutrient intake in Korean obese men with type 2 diabetes consuming a high carbohydrate diet.