Analyzing pump data

Medtronic equipment for continuous glucose monitoring system comes with SOLUTIONS pumps and meters software. This software is used to download the data from Paradigm pump and provides wide set of standard reports. These reports significantly help to improve diabetes control under normal conditions. But in case there is something wrong or non-standard, it is necessary to combine information from several of them into one. And this is not possible with SOLUTIONS pumps and meters software.

When the data is downloaded from the pump, it is saved into a file with the name
       {Last name}_{First name initial}_{Patient number}_{Download date}.mmp
in the directory
       ../MMSolutions/MM Solutions P & M/PatientData.
Downloaded mmp files are password protected Microsoft Access databases and contain data for about last 3 months.

The database consists of a few dozens of tables. All the table and field names are self explanatory, so it is relatively easy to read and understand it. I usually export data from MS Access file into Excel and create graphs / perform my analyses in Excel.

I found that there is a data error in table tblsensordetail containing ISIG readings and interstitial glucose values derived from ISIG. ISIG readings having value = 0 (occurring sometimes after new sensor insertion) are not recorded. This shifts ISIG and interstitial glucose profiles. The shift is none or low for data close to the download date and increases for data in the past. The difference can reach several hours. Interstitial glucose values are always recorded against the correct time while ISIG values are often delayed (recorded against later time). See Fig. 5a, 5b and 5c for the ISIG shift development.

Fig. 5a. ISIG shift on 3-rd June 2007

Fig. 5b. ISIG shift on 29-th April 2007

Fig. 5c. ISIG shift on 21-st March 2007

The analysis was performed on data downloaded on 13-th June 2007. The ISIG profile shift on Fig. 5a (data from 3-rd June 2007) is 5 minutes which corresponds to the delay described in the section "Sensor instrumental delay". The ISIG profile shift on Fig. 5b (data from 29-th April 2007) is 3 hours 15 minutes and the ISIG profile shift on Fig. 5c (data from 21-st March 2007) is 5 hours 45 minutes. Unfortunately this shift may make analyses based on ISIG values difficult. The best way to overcome it is to download data from the Paradigm pump every time just before the new sensor is inserted and merge data from several files if needed.