Objective To explore the effect of telmisartan combined with calcium dobesilate on hypertensive patients with type 2 diabetes mellitus （T2DM） on the blood pressure rhythm. Methods Patients with hypertension and T2DM who were treated in Hengshui people′s Hospital from January 2021 to December 2022 were selected as the study subjects. According to the principle of random grouping， the patients were divided into the control group （n = 115） and the observation group （n = 113）. Patients in the control group were treated with telmisartan （40 mg once daily）， while the patients in the observation group received additional calcium dobesilate treatment （0.5 g three times daily） on the basis of the treatment in the control group. Both groups of patients were treated for 12 months with follow-up visits every 3 months. The blood pressure indicators including 24-hour average systolic blood pressure （24 h SBP）， 24-hour average diastolic blood pressure （24 h DBP）， 24-hour average pulse pressure （24 h PP）， daytime average systolic blood pressure （dSBP）， daytime average diastolic blood pressure （dDBP）， daytime average pulse pressure （dPP）， nighttime average systolic blood pressure （nSBP）， nighttime average diastolic blood pressure （nDBP） and nighttime average pulse pressure （nPP）； blood glucose indicators including fasting blood glucose （FBG）， 2-hour postprandial blood glucose （2 h PG） and glycosylated hemoglobin （HBA1c）； endothelial function indicators including endothelin-1 （ET-1）， nitric oxide （NO） and vascular endothelial growth factor （VEGF）； and occurrence of adverse reactions during the medication period were statistically analyzed for both groups of patients. Results Before treatment， there were no statistically significant differences （P > 0.05） in the various indicators （blood pressure， blood glucose， endothelial function） between the two groups of patients. After 3， 6， and 12 months of treatment， the blood pressure indicators （24 h SBP， 24 h DBP， 24 h PP， dSBP， dDBP， dPP， nSBP， nDBP， nPP）， blood glucose indicators （FBG， 2 hPG， HBA1c）， and endothelial function indicators （ET-1） were significantly lower than before treatment in both groups of patients， and the levels of these above-mentioned indicators in the observation group were lower than those in the control group， with statistically significant differences （P < 0.05）. The levels of NO and VEGF in both groups of patients were significantly higher than before treatment， and the levels of NO and VEGF in the observation group were higher than those in the control group， with statistically significant differences （P < 0.05）. The incidence of adverse reactions during the medication period showed no statistically significant differences between the two groups of patients （P > 0.05）. Conclusion The combination of telmisartan combined with calcium dobesilate reduces blood pressure levels， regulates blood pressure rhythm， and improves endothelial function in patients with hypertension and T2DM， and shows favorable safety.