Table 1.

Characteristics of the cohorts included in the study

Study	N	Spectrometer	SF measure	Genotyping platform	Covariates
T1D
DCCT/EDIC	1,082	SCOUT DS	SIF	Illumina 1M	Age, sex, skin tone, clinic latitude, eGFR, smoking status, rs1495741 genotype*
WESDR	281	SCOUT DS	SIF	Illumina Omni-quad	Age, sex, skin tone, eGFR, smoking status, rs1495741 genotype†
ND plus T2D
LonGenity		SCOUT DS	SIF	Illumina HumanOmniExpress	Age, sex, skin tone, eGFR, smoking status‡
ND (OPEL)	192
ND (OPUS)	261
T2D	58
LifeLines		AGE Reader	SAF	Illumina CytoSNP 12v2	Age, sex, BMI, eGFR, smoking status, 10 first principle components§
ND	8,678
T2D	318

*Clinic latitude: categorized as a binary variable, with clinic located above 37° N latitude designated as northern clinics. eGFR: mean eGFR trough DCCT/EDIC calculated using annually measured serum creatinine and the Chronic Kidney Disease Epidemiology Collaboration equation (35). Smoking status during EDIC years 1–5, 6–10, and 11–16 as a continuous variable calculated by summing smoking status.

†eGFR: mean eGFR calculated using serum creatinine, measured almost every 5 years, and the Chronic Kidney Disease Epidemiology Collaboration equation (35). Smoking status: mean of smoking status, asked every 5 years through the study.

‡eGFR: eGFR calculated using serum creatinine and the Chronic Kidney Disease Epidemiology Collaboration equation (35). Smoking status: smoker vs. nonsmoker.

§eGFR: Cockcroft-Gault eGFR. Smoking status: smoker vs. nonsmoker.