Rate of rise for HbA1c during the first 1.5 years postdiagnosis
| Stratification (years) | HbA1c slope (±95% CI)* | Interaction p Value† | ||
|---|---|---|---|---|
| By age | ||||
| 0–4 | 0.15 (−0.02 to 0.32) | |||
| 5–9 | 0.87 (0.74 to 1.00) | |||
| ≥10 | 1.69 (1.58 to 1.80) | |||
| p Value‡ | <0.0001 | |||
| By race×age | Black | White | Other | p<0.001 |
| Overall | 2.04 (1.77 to 2.31) | 0.99 (0.91 to 1.08) | 1.38 (1.01 to 1.75) | |
| 0–4 | 0.19 (−0.26 to 0.64) | 0.10 (−0.044 to 0.24) | 0.70 (0.18 to 1.21) | |
| 5–9 | 1.60 (1.18 to 2.02) | 0.81 (0.70 to 0.92) | 1.16 (0.61 to 1.70) | |
| ≥10 | 3.04 (2.60 to 3.48) | 1.52 (1.38 to 1.67) | 2.00 (1.34 to 2.66) | |
| p Value‡ | <0.0001 | <0.0001 | 0.01 | |
| By diagnostic era×age | pre-2000 | 2000–2003 | 2004–2009 | p<0.001 |
| Overall | 0.92 (0.79 to 1.05) | 0.94 (0.78 to 1.09) | 1.36 (1.23 to 1.48) | |
| 0–4 | −0.07 (−0.28 to 0.13) | 0.10 (−0.15 to 0.36) | 0.42 (0.18 to 0.65) | |
| 5–9 | 0.77 (0.59 to 0.94) | 0.76 (0.55 to 0.98) | 1.02 (0.85 to 1.19) | |
| ≥10 | 1.59 (1.36 to 1.83) | 1.43 (1.16 to 1.70) | 1.93 (1.71 to 2.14) | |
| p Value‡ | <0.0001 | <0.0001 | <0.0001 | |
| By initial HbA1c×age§ | <7% (<53 mmol/mol) | 7–9%(53–75 mmol/mol) | >9% (>75 mmol/mol) | p<0.001 |
| Overall | 1.83 (1.72 to 1.94) | 0.81 (0.69 to 0.92) | −0.68 (−0.87 to −0.49) | |
| 0–4 | 1.15 (0.81 to 1.48) | 0.33 (0.13 to 0.53) | −0.99 (−1.40 to −0.59) | |
| 5–9 | 1.56 (1.38 to 1.74) | 0.55 (0.40 to 0.71) | −0.63 (−1.11 to −0.16) | |
| ≥10 | 2.08 (1.94 to 2.21) | 1.42 (1.25 to 1.60) | 0.45 (−0.90 to 0.00) | |
| p Value‡ | <0.0001 | <0.0001 | 0.19 | |
*Slope=ΔHbA1c/year (shown for NGSP (%) units only; NGSP*10.93=ΔHbA1c in SI/IFCC units (mmol/mol)).
†p Value for the interaction term testing whether the shape of the trajectory curve for each age-at-diagnosis subgroup changes across subgroups for the additional stratification variable (eg, race, diagnostic era, or initial HbA1c).
‡p Values represent comparison of slopes across the 3 diagnostic age subgroups (0–4, 5–9, and ≥10 years).
§Initial HbA1c=first HbA1c value obtained after initiation of insulin therapy.
HbA1c, glycated hemoglobin; NGSP, National Glycohemoglobin Standardization Program.