One of the presentations at EASD 2020 looked at whether adopting a low carb diet provided benefit to hybrid loopers. Given I know of low carb loopers that no longer declare meals I expected the answer to be “yes”, just like the cycling presentation, but I believe there is still value in looking at how the study was put together and what it specifically found. As usual we have tl;dr at the bottom if you want to cut to the chase.
Details of the Analysis
The presenter was Dr. Vera Lehmann.
Essentially, she looked at the data across 30 days of, based on the picture below, a Medtronic looping pump. Carbohydrate intake was taken from the participant declarations to the pump. In total there were 36 participants involved in the study.
To work out if lower carbohydrate intake affected Time in Range, rather than compare participants against each other, they took an average carb intake for each participant over 30 days and then measured their intake relative to this for each day.
Why did they not just compare the low carb folk to the high carb folk? I am not sure but perhaps this would introduce confounding factors e.g. perhaps low carb folk are skinnier than high carb folk and it could be the difference in weight causing the better control. By measuring to the individual, these issues are eliminated.
UPDATE: Dr. Lehmann was kind enough to respond to this question saying “We chose a relative approach to account for the intra- and interindividual variability in CHO intake and the confounding factors including weight (a tall, heavy man eats more carbs in grams per day than a small, lightweight woman). We could not categorize our population into low carb folk and high carb folk since there was a high variability in CHO intake between each day (some people had an individual range between 70 to 240 g carbs per day).”
There was not too much of a surprise in the results.
The low carbohydrate days had the highest Time in Range (blue) at around 80% but even the high carbohydrate days were not bad at around 70%.
For Time Above Range (green) the low carbohydrate days were up there for about 15% of the time and this went up to around 25% of the time for the high carbohydrate group.
No statistically significant conclusions could be drawn for Time Below Range.
What is interesting to me is that, even with the high carbohydrate days, the percentages were still within the recommended guidelines for diabetics.
Limitations acknowledged by the presented included:
- All participants were recruited from the same medical centre which means selection bias is possible
- The study was over a limited time period and longer time studies were recommended
- Carbohydrate quality and other macronutrients were not considered in the analysis
- Carbohydrate values were the estimated declarations of the participants with no validation of accuracy
- The participants were mostly male Caucasians
There is evidence that, even with a hybrid looping system, lower carbohydrate intake results in a better Time in Range (TIR) and a reduced Time Above Range (TAR). However, looking at the results, the TIR and TAR values were still within the recommended guidelines for the days when participants ate higher levels of carbohydrates than usual. In other words, if you are using a hybrid loop and you have the occasional carb-loaded day, it seems the looping system is sufficiently robust to keep it from being a complete disaster from a blood glucose perspective.
The exciting aspect of this for me is, assuming the TIR guidelines are accurate in minimising the risk of long term complications, as looping technology becomes more widespread, we should see a measurable reduction in such complications and a lot less mental stress for diabetics with automation making care management easier.