Continuous Glucose Monitoring in Youth with Pre-Type 1 Obesity/Pre-Type 2 Diabetes and Cystic Fibrosis

Continuous glucose monitoring abnormalities are present in the prediabetic state, but how these abnormalities compare among individuals at risk for different types of diabetes (type 1, type 2, vs. cystic fibrosis related diabetes) is unknown. We compared CGM patterns of three distinct groups of youth at risk for diabetes, all with A1c <6.5%: pre-T1D (multiple islet antibody positive), obese/pre-T2D (BMI ≥85^th%Ile), and cystic fibrosis (CF). None were on insulin or other medications affecting glucose metabolism. CGM was obtained for 3-7 days in our observational studies. Pre-T1D youth (A1c range 5.0-6.3%) were randomly matched 1:3 on A1c to the obese/pre-T2D and CF youth. Groups were compared using random effects models for continuous variables. Age, Sex distribution and HbA1c were not different between the groups after matching. The results are shown in the table. Of interest, youth with CF and pre-T1D had greater standard deviation, higher maximum and lower minimum glucoses than obese/pre-T2D youth.

In conclusion, CGM patterns are significantly different in pre-T1D and CF compared to obese/pre-T2D, reflecting differences in pathophysiology among these disease states. Early insulin deficiency appears to manifest as greater glycemic variability—higher SD, greater peaks and lows—in pre-T1D and CF, while insulin resistance leads to increased, but less variable, glucoses in obese/preT2D youth.