Type 2 diabetes mellitus (T2DM) may worsen autonomic recovery after ischemic stroke. A retrospective case-control study published in Journal of Diabetes Research found that patients with T2DM had persistently higher heart rate (HR) and lower heart rate variability (HRV), with the largest differences during nighttime and early morning hours.

The study included 157 patients with acute ischemic stroke who underwent 7-day continuous electrocardiographic monitoring, including 80 with T2DM and 77 without diabetes. Patients with paroxysmal atrial fibrillation, obstructive sleep apnea, or insufficient monitoring data were excluded. HR and HRV metrics were derived from repeated 5-minute segments and analyzed using generalized additive mixed models adjusted for demographic, clinical, and treatment factors.

Compared with patients without diabetes, those with T2DM showed lower HRV across time-domain measures, including standard deviation of NN intervals (SDNN), root mean square of successive differences (RMSSD), and pNN50, as well as lower frequency-domain indices including high-frequency (HF) and low-frequency (LF) power. HR remained higher despite preserved circadian rhythm patterns. The separation between groups was most pronounced during sleep and the early morning period.

Among patients with T2DM, glycated hemoglobin (HbA1c) >7% was associated with higher HR and lower HRV, particularly overnight, suggesting worse glycemic control aligned with greater autonomic dysfunction. These findings indicate continuous ECG monitoring may help identify high-risk post-stroke patients with occult nocturnal autonomic impairment.