Objective To observe the clinical effectiveness of manual release under brachial plexus block combined with high‑intensity laser therapy (HILT) in the treatment of scapulohumeral periarthritis patients with diabetes. Methods Scapulohumeral periarthritis patients with diabetes who were admitted to Department of Pain, the First Hospital of Qinhuangdao from December 2018 to December 2019 were selected. According to the random number table method, they were divided into two groups: a test group (group T, n=32) and a control group (group C, n=31). Patients in group T underwent manual release under brachial plexus block combined with HILT, while those in group C received manual release under brachial plexus block combined with intra‑articular injection of corticosteroid. Their shoulder pain and disability index (SPADI) were recorded before treatment (T0), one month after treatment (T1), two months after treatment (T2) and three months after treatment (T3). Both groups were compared for their Visual Analogue Scale (VAS) scores during movement, the Constant‑Murley (CM) score of the shoulder joint, the effective rate, adverse events, and the recurrence rate six months after treatment. Results The upper limits of 90% CI for the difference between the SPADI scores of both groups at T1, T2 and T3 and those at T0 were less than the non‑inferiority threshold. Compared with those at T0, both groups produced remarkable decreases in VAS scores, and increases in CM scores at T1, T2 and T3 (P<0.05). But there was no obvious difference between the two groups at the same time points (P>0.05); there was no marked difference in the effective rate between the two groups at T1, T2 and T3 (P>0.05). No serious adverse events were reported in each group, while six months after treatment, the recurrence rate of group T was significantly lower than that of group C (P<0.05). Conclusions The clinical effectiveness of manual release under brachial plexus block combined with HILT is non‑inferior to manual release combined with intra‑articular injection in scapulohumeral periarthritis patients with diabetes.