Introduction: Platelet morphology indices are indirectly related to platelet reactivity and may link glycemic exposure to cardiovascular risk.

Objectives: We aimed to investigate associations between continuous glucose monitoring (CGM)-derived metrics and platelet morphology in adults with T1DM.

Patients and methods: In this cross‑sectional study, we enrolled adults with T1DM without established cardiovascular disease. Platelet morphology indices were measured from fasting blood samples using the Sysmex XN‑1000 analyzer within 2 hours of blood collection. Glucose profiles were assessed using CGM over 7-, 14-, and 30‑day windows and calculated with Glyculator 3.0. We used Spearman correlation and multivariable linear regression models adjusted for age, sex, BMI, diabetes duration, C‑reactive protein, glomerular filtration rate, HbA1c, smoking, and platelet count.

Results: We included 301 adults with T1DM [median age 33.1 (24.1‑41.0), 44.5% men, diabetes duration 13 (7‑19) years]. Platelet large cell ratio (P‑LCR), mean platelet volume (MPV), and platelet distribution width (PDW)correlated positively with mean glucose (R = 0.27‑0.30), time above range (TAR) level 2 (P = 0.25‑0.29), glycemic risk index (R = 0.28‑0.30), and mean amplitude of glucose excursion (MAGE) (R = 0.20‑0.22), and inversely with time in range (R = −0.25 to −0.30; all P < 0.001), but not with hypoglycemia indices. In multivariable models, hyperglycemia‑related metrics remained independently associated with P‑LCR (standardized β 1.37‑1.59; ΔR² 0.014‑0.024; P = 0.002); MAGE lost significance in the multivariable model after accounting for TAR level 2.

Conclusion: In adults with T1DM, platelet morphology independently relates to cumulative hyperglycemic exposure rather than glycemic variability or hypoglycemia.