Telomeres do not always shorten over time in individuals with type 1 diabetes

We aimed to determine how white blood cell (WBC) telomeres and telomere length change over time are associated with health status in type 1 diabetes.Relative telomere length (rTL) was measured in WBC DNA from two time-points (median 6.8 years apart) in 618 individuals from the Finnish Diabetic Nephropathy Study by quantitative PCR, with interassay CV ≤ 4%.Baseline rTL correlated inversely with age and was shorter in men. Individuals in the shortest vs. longest rTL tertile had adverse cardiometabolic profiles, worse renal function, and were prescribed more antihypertensive and lipid-lowering drugs. While overall rTL tended to decrease during the median 6.8-years of follow-up, telomeres shortened in 55.3% of subjects, lengthened in 40.0%, and did not change in 4.7%. Baseline rTL correlated inversely with rTL change. Telomere lengthening was associated with higher HDL-Cholesterol (HDL-C), HDL-C/ApoA1, and with antihypertensive drug and (inversely) with lipid-lowering drug commencement during follow-up. Correlates of rTL percentage change per-annum (adjusted model) were baseline BMI, eGFR, previous retinal laser treatment, HDL-C, and HDL-C/ApoA1.Telomere length measurements may facilitate the treatment and monitoring of the health status of individuals with type 1 diabetes.