The effect of nutrition education using self-monitoring of blood glucose on glycemic control was investigated in the present study. Of 36 males and 25 females aged 30 - 69 years under outpatient treatment at 3 hospitals in Niigata prefecture, Japan, 61 non-insulin-treated obese type 2 diabetes patients with HbA1c of 6.9% - 9.3% and body mass index of 25 kg/m 2 or higher were randomly allocated. Thirty and 31 patients were analyzed in intervention and control groups, respectively. The intervention group performed self-monitoring of blood glucose 2 hours after supper twice a week for 6 months and underwent nutrition education on the association between meals and postprandial blood glucose once every 2 months. The primary outcome was glycated hemoglobin, with the secondary outcome of body mass index. Stages of change for eating the appropriate supper amount were investigated to verify the process of the educational effect, and satisfaction with diabetes treatment and well-being were investigated to verify the continuity of treatment. On intention-to-treat analysis, glycated hemoglobin (mean ± SD) decreased from 7.9% ± 0.6% to 7.7% ± 0.6% in the intervention group but increased from 7.9% ± 0.6% to 8.1% ± 0.6% in the control group, showing a significant difference in the change after intervention between the groups ( p = 0.027). In the intervention group, body mass index decreased from 28.9 ± 3.8 to 28.4 ± 3.7 kg/m 2 ( p = 0.019), the stages of change to learn the appropriate amount of supper progressed ( p = 0.026), and satisfaction with diabetes treatment increased ( p = 0.031).
The objective of diabetes treatment is to inhibit the development and progression of complications. The importance of glycemic control for inhibition of complications has been investigated in various large-scale clinical studies [
In our previous study [
In addition, it has been reported that SMBG and intervention based on the educational programme, based on face-to-face encounters every 3 months and additional telephone contacts every month, significantly improved glycemic control [
Thus, we investigated the effects of nutrition education using SMBG and newly developed educational tools on glycemic control in non-insulin-treated obese type 2 diabetes patients.
A randomized controlled study was performed.
36 males and 25 females non-insulin-treated obese (Body mass index (BMI) over 25 kg/m2), type 2 diabetes patients aged 30 - 69 years with HbA1c of 6.9% - 9.3% and treated in the outpatient clinic in Niigata Medical Center, Nagaoka Chuo General Hospital, and Kariwagun General Hospital in Niigata prefecture, Japan, who gave consent for this study were registered. Those who had changed medication 6 months prior to the time of intervention (March 2010) were excluded. Sixty-one patients at the 3 hospitals were stratified according to the hospital, gender, age, BMI, and HbA1c and randomly allocated to intervention (n = 30) and control (n = 31) groups. To estimate the target sampling size, the endpoint was set to HbA1c reduction, and the reduction by intervention and that in the control group were assumed to be –0.5 and 0%, respectively, referring to a previous study [
The assessment period was set between September 2010 and February 2011. In the intervention group, patients measured the blood glucose level 2 hours after supper twice a week (weekdays and holidays) for 6 months, and recorded the following items on an “SMBG record form”: the content of the meal and blood glucose level 2 hours after the meal, place where the meal was eaten, presence or absence of exercise after the meal, and self-evaluation of the association between the meal and blood glucose level. Patients attended nutrition education concerning the association between blood glucose and meals using educational tools when they visited the hospital once every 2 months (3 times in total). The control group attended nutrition education without SMBG using the same educational tools once every 2 months. Target BMI and HbA1c after 6 months were set in the first session of nutrition education in both groups, but physicians were not informed of the target values, registered dietitians managed these values. Nutrition education was performed by the same registered dietitian at Niigata Medical Center and 4 registered dietitians each at the 2 other hospitals, using the same educational media and content, and the frequencies of assignment to the intervention and control groups were adjusted to be the same by each registered dietitian. The SMBG procedure was explained by a clinical technologist at Niigata Medical Center, a nurse at Nagaoka Chuo General Hospital, and a registered dietitian at Kariwagun General Hospital.
Prior and post surveys were performed in September 2010 and March 2011, respectively. The primary outcome was HbA1c, and the secondary outcome was BMI. In addition, the stages of change for eating the appropriate supper amount (the stages of change) were investigated to verify the process of the educational effect, and satisfaction with diabetes treatment and well-being were investigated to verify the continuity of treatment. Survey items were height, weight, and HbA1c on blood testing, satisfaction with diabetes treatment, well-being, the stages of change, and execution of exercise. Satisfaction with diabetes treatment was assessed using Bradley’s questionnaire (8 items) translated into Japanese by Ishii [
For SMBG, ONE TOUCH Ultra Vue (Johnson & Johnson Co., Ltd.) was used, and the device was provided to patients out of our research funds. SMBG was performed at the patients’ home, and blood testing, questionnaires, and nutrition education took place at each hospital. Survey results were analyzed at the Diabetes Center of Niigata Medical Center. HbA1c was measured using an automatic glycohemoglobin measurement device, ADAMS A1c HA-8170, at Niigata Medical Center and Kariwagun General Hospital, and JCA-BM2250 (Nihon Denshi) at Nagaoka Chuo General Hospital. HbA1c is presented as National Glycohemoglobin Standardization Program (NGSP) values (=Japan Diabetes Society (JDS + 0.4%) [
In statistical analysis, after the test for normality, changes in HbA1c and BMI after intervention were analyzed using the paired t-test, and differences in changes after intervention between groups were analyzed using the unpaired t-test. The Wilcoxon signed-ranks test was employed for analysis of changes after intervention in the scores of attitude and behavior, and between-group differences in changes after intervention were analyzed using the Mann-Whitney test. For analysis of betweengroup differences in the change in exercise after intervention, the χ2 test of independence was employed. SPSS 19.0 for Windows was used for data analysis.
Subjects included in analysis are shown in
Regarding ethical considerations, this study was performed conforming to the Declaration of Helsinki after examination and approval by the Ethics Committees of Niigata Medical Center and Niigata University of Health and Welfare. Examination and approval were also obtained from the Ethics Committees of collaborating hospitals, Nagaoka Chuo General Hospital and Kariwagun General Hospital. Collaboration by patients was optional, and written informed consent was obtained. Data were managed by assigning IDs to prevent identification of individual patients.
The text of the nutrition education tool was composed of: 1) “To improve postprandial hyperglycemia and achieve appropriate HbA1c”, and 2) “Real-size photographs of dishes to learn the appropriate amounts of single meals”.
1) “To improve postprandial hyperglycemia and achieve appropriate HbA1c”
This section was as follows to facilitate understanding of the association between postprandial blood glucose and meals: (1) Why is postprandial blood glucose important? (2) Postprandial blood glucose and nutrients (including figures presenting “the speeds of conversion and ratios of nutrients to blood glucose) [
2) “Real-size photographs of dishes to learn the appropriate amounts of single meals”
To facilitate the understanding of items 1, 2, 3, and 5 of the “important points of meals”, “the appropriate amounts of single meals” of related dishes were presented as real-size photographs. For item 4, photographs were omitted because it is easy for Japanese to identify appropriate amounts. Six dishes to reduce carbohydrates to a specific amount were presented with regards to staple food, such as those containing vegetables high in carbohydrates, such as potatoes and pumpkin, and gyoza containing wheat flour. Regarding the main dish, 8 dishes were presented, such as mixed proteinaceous foods and vegetables (e.g. boiled chicken and vegetables) and main dishes that tended to be eaten excessively (fried chicken and Chinese dishes). Real-size photographs of meals actually served to diabetes patients admitted to Niigata Medical Center were presented. To facilitate understanding of the amounts in the photographs, not only the energy, but also the weight (g), size, and number of pieces were presented numerically (e.g. 3 cm in length × 3 cm in width), and the approximate amount of 1 unit was also presented. For photographs of main dishes, the ratio of fat in one meal was presented, in addition to nutrition labeling of energy and fat. Tableware size was also presented in each photograph to facilitate understanding of the appropriate amount.
In the intervention group, 1) and 2) were used as nutrition education tools. In the control group, the same tools were basically used, but the “Look-back check list” was omitted from 1).
To perform identical nutrition education, registered dietitians at the 3 hospitals underwent training in the effective use of nutrition education tools.