Table 1. Baseline Characteristics Before and After Propensity Score Overlap Weighting in 5673 Patients With Type 1 Diabetes, January 1, 2015, Through December 31, 2018.
| Variables | Crude (unweighted)a | Standardized differencec | After overlap weightinga,b | Standardized differencec | ||
|---|---|---|---|---|---|---|
| Real-time CGM initiators (n = 3462) | Noninitiators (n = 2211) | Real-time CGM initiators (n = 3462) | Noninitiators (n = 2211) | |||
| Male | 48.2 | 57.8 | −0.19 | 52.7 | 54.2 | −0.03 |
| Female | 51.8 | 42.2 | 0.19 | 47.3 | 45.8 | 0.03 |
| Age, mean (SD), y | 40.7 (19.6) | 45.2 (18.7) | −0.23 | 42.8 (19.3) | 42.8 (19.0) | 0.00 |
| Age at diabetes onset, mean (SD), y | 20.8 (15.0) | 24.7 (15.8) | −0.26 | 22.1 (15.3) | 22.2 (15.3) | −0.01 |
| No. | 2442 | 1574 | 2442 | 1574 | ||
| Diabetes duration, mean (SD), y | 18.4 (15.5) | 19.9 (15.3) | −0.10 | 19.5 (15.7) | 19.4 (15.7) | 0.01 |
| No. | 2442 | 1574 | 2442 | 1574 | ||
| Race/ethnicityd | ||||||
| White | 74.0 | 66.4 | 0.16 | 70.3 | 71.4 | −0.02 |
| Hispanic | 8.8 | 12.8 | −0.13 | .9 | 9.9 | 0.03 |
| Black | 5.2 | 8.2 | −0.12 | 6.6 | 6.9 | −0.01 |
| Asian | 5.7 | 6.9 | −0.05 | 6.0 | 5.9 | 0.01 |
| Multiracial/multiethnic | 5.7 | 6.9 | −0.05 | 6.0 | 5.9 | 0.01 |
| Other | 0.6 | 1.1 | −0.06 | 1.1 | 0.7 | 0.03 |
| Unknown | 1.6 | 0.9 | 0.06 | 1.3 | 1.4 | −0.01 |
| Preferred spoken language not English8 | 1.1 | 2.2 | −0.09 | 1.7 | 1.2 | 0.05 |
| Neighborhood deprivation indexe | ||||||
| No. | 3430 | 2180 | 3430 | 2180 | ||
| Q1 (least deprived) | 29.3 | 22.7 | 0.15 | 25.6 | 27.0 | −0.03 |
| Q2 | 32.5 | 30.2 | 0.05 | 31.1 | 30.5 | 0.01 |
| Q3 | 25.1 | 28.6 | −0.08 | 26.8 | 27.4 | −0.01 |
| Q4 (most deprived) | 12.2 | 17.1 | −0.14 | 15.4 | 14.0 | 0.04 |
| Insurance typef | ||||||
| Commercial | 92.4 | 90.8 | 0.06 | 90.9 | 90.8 | 0.01 |
| Medicare Advantage | 17.2 | 22.0 | −0.12 | 20.1 | 20.0 | −0.01 |
| Medicaid | 8.6 | .4 | −0.06 | 10.0 | 10.5 | 0 |
| Charlson Comorbidity scoreg | ||||||
| 1 | 46.6 | 45.4 | 0.02 | 45.1 | 45.4 | −0.01 |
| 2 | 33.7 | 28.7 | 0.11 | 32.2 | 32.2 | 0 |
| 3 | 6.0 | 5.4 | 0.03 | 5.5 | 5.8 | −0.01 |
| ≥4 | 13.7 | 20.5 | −0.18 | 17.2 | 16.7 | 0.01 |
| Hypoglycemia risk scoreh | ||||||
| Low | 70.8 | 66.8 | 0.09 | 68.5 | 68.5 | 0 |
| Intermediate | 7.9 | 10.2 | −0.08 | 8.8.7 | 8.2 | 0.02 |
| High | 21.4 | 23.0 | −0.04 | 22.7 | 23.4 | −0.02 |
| Insulin type | ||||||
| Long acting | 62.0 | 72.6 | −0.23 | 74.0 | 75.6 | −0.04 |
| NPHi | 4.5 | 16.7 | −0.41 | 6.6 | 6.6 | 0 |
| Rapid acting | 98.6 | 84.9 | 0.51 | 95.9 | 97.8 | −0.11 |
| Short acting | 3.0 | 14.0 | −0.40 | 5.0 | 4.8 | 0.01 |
| Mixed | 0.3 | 2.6 | −0.20 | 0.5 | 0.6 | −0.02 |
| Glucagonj | 35.5 | 13.2 | 0.54 | 21.6 | 21.6 | 0 |
| Insulin delivery | ||||||
| Pen | 27.4 | 39.3 | −0.25 | 40.3 | 42.6 | −0.05 |
| Pumpk | 57.3 | 15.0 | 0.98 | 30.6 | 30.6 | 0 |
| ≥3 Insulin injections/d | 7.7 | 17.0 | −0.28 | 13.1 | 12.2 | 0.03 |
| Self-monitoring of blood glucose | ||||||
| <1/d | 0.9 | 4.9 | −0.24 | 1.6 | 1.4 | 0.01 |
| ≥1/d | 99.1 | 95.1 | 0.24 | 98.4 | 98.6 | −0.01 |
| HbA1c, mean (SD), %l | 8.16 (1.5) | 8.40 (1.8) | −0.15 | 8.22 (1.6) | 8.33 (1.8) | −0.06 |
| No. | 3114 | 1910 | 3114 | 1910 | ||
| Hypoglycemic eventm | 4.9 | 3.4 | 0.07 | 4.4 | 4.2 | 0.01 |
| Hyperglycemic eventm | 4.8 | 4.8 | −0.003 | 4.7 | 5.2 | −0.02 |
| Any ED visitn | 29.5 | 29.1 | 0.01 | 29.3 | 29.0 | 0.01 |
| Any hospitalizationn | 4.6 | 5.9 | −0.06 | 5.1 | 5.9 | −0.04 |
| No. of visits, mean (SD)n | ||||||
| Outpatient | 5.0 (3.7) | 2.8 (3.0) | 0.66 | 3.8 (3.6) | 3.8 (3.6) | 0 |
| Telephone | 4.2 (5.5) | 3.3 (4.6) | 0.18 | 4.0 (5.6) | 3.5 (4.8) | 0.09 |
Abbreviations: CGM, continuous glucose monitoring; ED, emergency department; HbA1c, hemoglobin A1c; NPH, neutral protamine Hagedorn; Q, quartile.
Column percent unless otherwise specified.
Propensity score models were based only on the variables included in eTable 1 in the Supplement.
The standardized difference (d) compares characteristics for real-time CGM initiators with noninitiators (reference group). An absolute value of d of 0.1 or lower indicates a negligible difference in the mean or in the prevalence of a covariate between groups.9
Self-reported race/ethnicity from the electronic health record. Multiracial/multiethnic means more than 1 of the racial/ethnic categories was selected.
The neighborhood deprivation index10 is a validated, contextual measure of socioeconomic status derived by linking each participant’s geocoded residential address to census tract level socioeconomic indicators as reported in the 2010 American Community Survey.
Kaiser Foundation Health Plan is the provider of all insurance and does not offer Medicare fee-for-service; insurance types are not mutually exclusive.
Based on the modified version of the Deyo Charlson Index score11 using inpatient and outpatient diagnosis and procedure codes. Possible scores ranged from 0 to 20 and represent the number of comorbid conditions identified (excluding diabetes) during the 12 months before baseline.
This validated risk stratification score12 predicts the 12-month risk of hypoglycemia-related utilization using electronic medical records data; the score was categorized as low (<1%), intermediate (1%-5%), and high (>5%).
Insulin types are not mutually exclusive.
Glucagon dispensed from a pharmacy may be an indicator of higher risk of a hypoglycemic event.
Users of both pen and pump were categorized as pump users.
Last HbA1c recorded during the 12 months before baseline. HbA1c was included in propensity score models used for outcomes other than HbA1c, eg, hypoglycemia and hyperglycemia. It appears both in this Table as a baseline measure and as an outcome measure. The same is true of hypoglycemic and hyperglycemic events, ED encounters, hospitalizations, and outpatient visits.
Identified by a principal diagnosis in the inpatient setting or a primary diagnosis in the emergency department during the 12 months before baseline.
Utilization captured during the 12 months before baseline.