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In patients with type 1 diabetes (T1D), protein- and carbohydrate-based insulin dosing does not improve glycemic control compared with carbohydrate-based dosing alone.
- Patients with type 1 diabetes may have difficulty controlling postprandial blood glucose levels when following a carbohydrate-restricted diet.
- Researchers evaluated the effect of additional bolus insulin with carbohydrate- and protein-based insulin delivery on glycemic control in patients with type 1 diabetes.
- Participants were randomly assigned (1:1) to receive either carbohydrate- and protein-based insulin or carbohydrate-based insulin (control group) for 12 weeks, and all followed a carbohydrate-restricted diet (50-100 g per day).
- Participants in the intervention group self-administered mealtime bolus insulin based on insulin-to-carbohydrate ratio (ICR) and top-up doses using insulin-to-protein ratio (IPR), whereas the control group used ICR only.
- The primary outcome was A1c levels at 12 weeks, and secondary outcomes were glycemic variability, mean blood glucose levels, range (4.0-10.0 mmol/L) and time spent in hyperglycemic (> 10 mmol/L) and hypoglycemic (< 4.0 mmol/L) ranges.
- The researchers enrolled 34 adult participants (mean age 39.2 years, 64.7% women, mean duration of diabetes 20.6 years).
- At 12 weeks, the use of carbohydrate- and protein-based insulin doses did not lead to greater improvements in A1c levels compared with the use of carbohydrate-based insulin doses alone (P = .65).
- Supplemental protein-based insulin administration improved glycemic variability (P = .048), but after adjusting for multiple comparisons, the results were not significant.
- Mean blood glucose levels, time spent in range, and time spent with hyperglycemia or hypoglycemia did not differ between the two groups.
- Many participants in the carbohydrate- and protein-based dosing group reported the inconvenience, stress, and anxiety of having to count protein in addition to carbohydrates.
“It would be of great interest to investigate the use of IPR in addition to ICR in individuals with higher baseline A1c levels, although it would have been preferable to include higher A1c levels in this study. The differences in blood glucose variability observed with the use of additional IPR suggest a potential clinical benefit,” the authors wrote.
The study was led by Rosemary M. Hall of the University of Otago School of Medicine in Wellington, New Zealand. online In Journal of Diabetes and its Complications.
The sample size was relatively small, which may have affected the power of the study. Lower baseline A1c levels than were used in the study's power calculations may have overestimated the predicted effect size. There was a large difference in duration of diabetes between the randomized groups, which may confound the study results.
This research was supported by the Maurice and Phyllis Paykel Foundation and the Wellington Medical Research Foundation. The authors declare that they have no conflicts of interest.