Table 3.
Comparison of glycemic control over 12 months among CGM users and nonusers with T1D or T2D
| Analysis | CGM users | Non-CGM users | Weighted difference in differences | |||||
|---|---|---|---|---|---|---|---|---|
| Before baseline | After baseline | Difference | Before baseline | After baseline | Difference | Estimate (95% CI) | P | |
| T1D (CGM users, n = 4,930; nonusers, n = 3,263) | ||||||||
| Mean (SD) HbA1c at 6 months, % | 8.54 (1.45) | 8.26 (1.33) | −0.28 | 8.39 (1.56) | 8.36 (1.55) | −0.03 | −0.26 (−0.31, −0.21) | <0.001 |
| Mean (SD) HbA1c at 12 months, % | 8.54 (1.45) | 8.22 (1.35) | −0.32 | 8.39 (1.56) | 8.39 (1.55) | 0.0 | −0.26 (−0.33, −0.19) | <0.001 |
| HbA1c <7%, % | 11.5 | 14.8 | +3.3 | 16.5 | 16.4 | −0.1 | 3.4 (−17.7, 24.5) | 0.75 |
| HbA1c <8%, % | 38.9 | 47.0 | +8.1 | 43.2 | 44.5 | +1.3 | 6.9 (0.1, 13.6) | <0.05 |
| HbA1c <9%, % | 66.0 | 75.7 | +9.7 | 70.0 | 69.9 | −0.1 | 9.7 (7.7, 11.8) | <0.001 |
| T2D (CGM users, n = 15,292; nonusers, n = 28,467) | ||||||||
| Mean (SD) HbA1c at 6 months, % | 8.70 (1.71) | 8.17 (1.42) | −0.53 | 8.26 (1.61) | 8.13 (1.58) | −0.13 | −0.39 (−0.42, −0.36) | <0.001 |
| Mean (SD) HbA1c at 12 months, % | 8.70 (1.71) | 8.21 (1.46) | −0.49 | 8.26 (1.61) | 8.10 (1.60) | −0.16 | −0.35 (−0.40, −0.31) | <0.001 |
| HbA1c <7%, % | 12.2 | 17.2 | +5.0 | 19.2 | 23.7 | +4.5 | 0.4 (−8.2, 9.0) | 0.92 |
| HbA1c <8%, % | 36.6 | 49.6 | +13.0 | 49.1 | 54.7 | +5.6 | 7.4 (4.6, 10.2) | <0.001 |
| HbA1c <9%, % | 63.1 | 76.2 | +13.1 | 73.2 | 76.3 | +3.1 | 10.0 (9.1, 10.9) | <0.001 |
Abbreviations: CGM, continuous glucose monitoring; CI, confidence interval; HbA1c, hemoglobin A1c (%); n, sample size; mo, months; T1D, type 1 diabetes; T2D, type 2 diabetes.
P values <0.05 and associated estimates are in bold. Values presented before or after baseline as mean (SD) or percentage. Sample size is slightly reduced for HbA1c outcomes because those included must have either a preindex HbA1c value, a 6-month postindex value, or a 12-month postindex value. Difference-in-differences estimates reflect LMMs and GEEs with HbA1c status within 6 months before and 12 months after the index date adjusted by overlap weighting from PS models. The reference group for comparisons is CGM nonusers. To convert HbA1c from percentage to mmol/mol, use the formula HbA1c, mmol/mol = (HbA1c, % − 2.152) ÷ 0.09148.