Table 3.

Association of Log(Skin Intrinsic Fluorescence) with Varying Glycemic Exposure Intervals

	β (R2) at glycemic exposure interval
	EDIC
	Last 5 years	Last 10 years	All years	EDIC+DCCT	EDIC+DCCT+baselinea
Mean HbA1c (%)	0.028 (0.023)	0.032 (0.027)	0.037 (0.033)	0.043 (0.038)	0.048 (0.045)
Age (years)	0.011 (0.137)	0.011 (0.137)	0.011 (0.136)	0.011 (0.146)	0.012 (0.147)
Any eGFR <60 mL/min/m2 to date (yes vs. no)	0.140 (0.030)	0.133 (0.027)	0.122 (0.022)	0.113 (0.019)	0.106 (0.016)
Smoking (current, former, never)b	0.070 (0.058)	0.069 (0.056)	0.067 (0.053)	0.067 (0.053)	0.066 (0.052)
Skin tone (arbitrary units)	0.0008 (0.034)	0.0008 (0.034)	0.0008 (0.034)	0.0008 (0.036)	0.0008 (0.034)
Clinic latitude >37o (south vs. north)	0.055 (0.014)	0.057 (0.015)	0.056 (0.015)	0.058 (0.015)	0.057 (0.015)
Total R2 (all variables)	0.308	0.314	0.320	0.325	0.331

Data are β coefficients and squared semipartial R² correlations from five separate linear regression models regressing log(skin intrinsic fluorescence) on various glycemic exposure intervals. Each model was simultaneously adjusted for age, any estimated glomerular filtration rate (eGFR) <60 mL/min/m², smoking status, skin tone, and clinic latitude.

^aTotal mean hemoglobin A1c (HbA1c) is calculated by summing (Diabetes Control and Complications Trial [DCCT]/Epidemiology of Diabetes Intervention and Complications [EDIC] eligibility HbA1c×duration of diabetes at study baseline), (DCCT mean HbA1c×years of follow-up on DCCT), and (EDIC mean HbA1c×years of follow-up in EDIC) and dividing by total duration of diabetes.

^bCurrent smoker defined as currently smoking or smoking within the last year; ever smoker defined as smoking more than a year ago.