AIMS: To evaluate the heart rate fragmentation (HRF) of type 2 diabetes mellitus (T2DM) patients and its relationship with heart rate variability (HRV) indices. METHODS: One hundred sixty-four men, aged 47-57 years were retrospectively analyzed from a database. Participants were T2DM (n = 82) and apparently healthy (n = 82). R-R interval time series recorded by electrocardiogram were collected at the supine position for 10 to 15 min. From HRF, the percentage of inflection points (PIP), percentage of words with zero, one, two, or three inflections points (W(0), W(1), W(2), W(3)), and percentage with only type hard, soft, or mixed inflections points type (W(H), W(S), W(M)) were quantified. RESULTS: T2DM presented higher PIP, W(S), W(M) and W(3), while W(H) and W(1) was lower compared with healthy (p < 0.05). Moreover, a positive moderate correlation was found between W(H) and root mean square of the successive R-R differences (RMSSD) and high frequency (HF) indices. In contrast, a negative moderate correlation was found between W(S) and W(M) with RMSSD and HF indices. CONCLUSIONS: T2DM have increased fragmentation patterns, and words grouped by inflection type are more closely related to HRV. The HRF approach might be useful to assess heart rate dynamic abnormalities in males with type 2 diabetes.