There is a lack of data on how to treat hypertensive patients with diabetes when treatment with medium doses of calcium channel blocker and angiotensin II type 1 receptor blocker (ARB) is insufficient to achieve the target blood pressure (BP). A total of 121 participants with type 2 diabetes and uncontrolled essential hypertension, who were receiving medium doses of amlodipine (5 mg/day) and ARB, were enrolled. Participants were randomized to receive either a high dose of amlodipine (10 mg/day) plus a medium dose of ARB (high-AML) or a medium dose of amlodipine (5 mg/day) plus a high dose of ARB (high-ARB). The depressor effects of these two regimens were monitored using a telemonitoring home BP-measuring system. Fifty-four patients were excluded after an observation period, and the remaining 67 eligible participants were randomized into the two groups; 42 which had a record of their home BP for analysis. The change in morning home systolic and diastolic BP was greater in the high-AML than in the high-ARB (systolic BP; − 7.9 mmHg vs. + 2.7 mmHg; p = 0.0002, diastolic BP; − 3.9 mmHg vs. + 0.6 mmHg; p = 0.0007). In addition, the home systolic and diastolic BP before going to bed and office systolic BP were significantly reduced from week 0 only in the high-AML. An increased dose of amlodipine, but not ARB, reduced home morning BP in hypertensive patients with type 2 diabetes who were already receiving combination therapy with medium doses of amlodipine and ARB.