Optimal energy distribution of carbohydrate intake for Japanese elderly patients with type 2 diabetes: The Japanese Elderly Intervention Trial

Aim: In diet therapy for diabetes, optimal energy intake and the energy distribution of macronutrients (protein : fat : carbohydrate [PFC] energy ratio) are important. We aimed to clarify the correlation between the PFC energy ratio and metabolic parameters including glycated hemoglobin A1c (HbA1c) and triglycerides in Japanese elderly patients with type 2 diabetes mellitus aged 65 years or older. Methods: Participants were 1173 diabetic patients aged 65 years or older with serum HbA1c level of >= 7.4% enrolled in the Japanese Elderly Diabetes Intervention Trial (J-EDIT). The participants were divided into four groups by the percentage of total energy intake (% E) of carbohydrate (C1: less than 55% E, C2: 55% E or more and less than 60% E, C3: 60% E or more and less than 65% E, and C4: 65% E or more). Relations of % E of carbohydrate to HbA1c and other metabolic parameters, energy intake and nutritional intake were examined. Furthermore, the subjects were divided into four categories by HbA1c levels by quartile method (Q1: less than 7.90%, Q2: 7.90% or more and less than 8.30%, Q3: 8.30% or more and less than 8.80%, Q4: 8.80% or more). Relations of HbA1c to other metabolic parameters, energy intake and nutritional intake were examined. Results: The mean HbA1c levels in the four groups were C1: 8.40%, C2: 8.50%, C3: 8.41% and C4: 8.36% in men, and C1: 8.51%, C2: 8.47%, C3: 8.35% and C4: 8.52% in women, respectively. There were no significant differences and linear trend in HbA1c levels across groups. The mean triglyceride levels were in the range of 122-128 mg/dL in triglyceride levels were in the range of 128-136 mg/dL in women from C1 to C3, although it was significantly higher in Q4 (150 mg/dL). Amounts of protein and fat intakes decreased with an increase of % E of carbohydrate, although amount of carbohydrate intake did not change significantly. As a result, % E of protein and fat, and energy intake decreased in both men and women with an increase in % E of carbohydrate. Among the four quartiles divided by HbA1c levels, there were no significant differences in energy intake and PFC energy ratio. Conclusions: The present study suggests that, within the range studied, the carbohydrate energy ratio has no correlation with HbA1c levels. However, serum triglyceride levels increased and high-density lipoprotein cholesterol levels decreased significantly, with an increase of % E of carbohydrate in men, and the same tendencies were observed in women. Furthermore, in patients with 65% E or more of carbohydrate, serum triglyceride levels exceeded 150 mg/dL, which is the recommended treatment target for diabetic patients. These results suggest that the ideal % E of carbohydrate for Japanese elderly type 2 diabetes is less than 65. The lower limit of % E of carbohydrate could not be determined from the present study. Geriatr Gerontol Int 2012; 12 (Suppl. 1): 41-49.