Letter to the Editor
Continuous subcutaneous insulin infusion (CSII) is widely used in the United States;1 however, the percentage of CSII usage among type 1 diabetes mellitus (T1DM) patients in Japan has been unclear. We performed a cross-sectional study of CSII usage among T1DM patients at 11 National Hospital Organization (NHO) hospitals in Japan.
The survey was conducted complying the regulations of NHO that obtain informed consent from all the patients allowing the statistical analysis of the medical records on condition that the privacy of the patients is strictly protected, unless the patients opt out.2 The medical records of 493 adult T1DM patients were analyzed. The percentage of CSII usage was investigated, and the characteristics of subjects using CSII and subjects using multiple daily injections (MDI) were compared. The percentages of CSII usage between different age groups (age group 1: 18-24 years old, age group 2: 25-64 years old, age group 3: 65+ years old) were also compared. The survey was conducted between April 2010 and March 2012. Data were analyzed using the Statistical Package for Social Science software version 20.0 (SPSS Inc, Chicago, IL, USA).
The characteristics of subjects using MDI and subjects using CSII are described in Table 1. The mean age of the patients was 48.7 years old (SD 17.0 years), and 57.0% were female. The percentage of CSII usage was 15.0%. Compared to subjects using MDI, subjects using CSII were younger (MDI: 50.1 ± 17.2 years old vs CSII: 40.5 ± 13.1 years old; P < .01), and female dominant (MDI: 54.2% vs CSII: 73.0%; P < .01). There was no significant difference in the mean HbA1c levels (MDI: 8.4 ± 1.6% vs CSII: 8.1 ± 1.6%; P = .27). The percentage of CSII usage was significantly higher in age group 1 and was significantly lower in age group 3 (23.5% in age group 1, 17.1% in age group 2, 4.1% in age group 3, P = .002).
Table 1.
Characteristics of Patients With Type 1 Diabetes Using MDI or CSII.
| Variable | MDI (n = 419) | CSII (n = 74) | P value |
|---|---|---|---|
| Age | 50.1 (17.2) | 40.5 (13.1) | <.01* |
| Male, % (male/female) | 45.8% (192/227) | 27.0% (20/54) | <.01* |
| Body mass index, kg/m2 | 21.8 (3.2) | 22.1 (3.0) | .41 |
| Diabetes duration | 13.8 (10.9) | 11.8 (8.6) | .08 |
| HbA1c, % | 8.4 (1.6) | 8.1 (1.6) | .26 |
| HbA1c <7% | 19.2% | 25.4% | .25 |
| Systolic blood pressure, mmHg | 126.4 (18.5) | 121.7 (15.8) | .04* |
| Diastolic blood pressure, mmHg | 73.1 (11.6) | 73.4 (10.0) | .81 |
| Anti-hypertensive agents, % | 26.8% | 17.6% | .11 |
| <130/80 mmHg | 55.2% | 71.2% | .01* |
| LDL-cholesterol, mg/dL | 106.9 (29.5) | 106.3 (32.0) | .87 |
| <120 mg/dL | 69.0% | 65.2% | .58 |
| Retinopathy | 19.6% | 13.5% | .01* |
| Photocoagulation | 6.9% | 9.5% | .65 |
| Nephropathy | 70.2% | 85.7% | . 02* |
| No | 29.8% | 14.3% | |
| Yes | |||
| Microalbuminuria | 15.0% | 4.1% | .12 |
| Macroalbuminuria | 11.3% | 8.2% | |
| End-stage renal disease | 3.4% | 2.0% |
Values are presented as mean with standard deviation in parentheses or percentage. Student’s t-test was used to compare the means of the two groups for continuous variables. One-way ANOVA analysis was performed to compare the means of the three groups for continuous variables. A chi-square test was used to compare proportions for categorical variables. Those cases with missing data were omitted in the relevant analysis.
P < .05.
To our knowledge, this is the first multicenter survey of the percentage of CSII usage among T1DM patients in Japan. The percentage of CSII usage was low and CSII was more commonly used in younger adults and less commonly used in elderly adults. The mechanism why CSII usage was low in Japan needs to be addressed in future study. One hypothesis is that, due to the legal requirements in Japan, insulin pump manufacturers are not allowed to send their pump trainers to medical institutes or patients directly, and this restriction might be a barrier to more frequent usage of insulin pump. The reason why there was no significant difference in the HbA1c levels between CSII and MDI in this survey also remains unclear. In another small study conducted in Japan, the HbA1c levels of T1DM patients using CSII were significantly lower than those using MDI.3 There might be difference in the insulin pump education or patient background between different medical institutions. We need to note the presented data are 5 to 7 years old and might or might not be accurate at this time. In 2015, the sensor-augmented pump became commercially available in Japan, and further study is needed to follow up the usage of CSII.
Acknowledgments
The following institutions participated in this study. NHO Kyoto Medical Center, NHO Matsumoto Medical Center Matsumoto Hospital, NHO Nagoya Medical Center, NHO Mie Chuo Medical Center, NHO Mie Hospital, NHO Osaka Medical Center, NHO Okayama Medical Center, NHO Kure Medical Center, NHO Zentsuji Hospital, NHO Higashisaga Hospital, and NHO Kumamoto Medical Center.
Footnotes
Abbreviations: CSII, continuous subcutaneous insulin infusion; MDI, multiple daily injections; NHO, National Hospital Organization; T1DM, type 1 diabetes mellitus.
Declaration of Conflicting Interests: The author(s) declared the following potential conflicts of interest with respect to the research, authorship, and/or publication of this article: TM discloses the following relationships: lecture fee from Novo Nordisk, Eli Lilly, Sanofi, MSD; grants paid to institution as study physician by Novo Nordisk, Sanofi, Kissei, Ono, Astellas. TT discloses the following relationships: lecture fee from Eli Lilly, Taisho Toyama, MSD, Boehringer Ingelheim, Astellas. NS discloses the following relationships: lecture fee from Novo Nordisk, Eli Lilly, Sanofi.
Funding: The author(s) disclosed receipt of the following financial support for the research, authorship, and/or publication of this article: This study was supported by Grant-in-Aid from NHO (H26-NHO(Diabetes)-03).
References
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