Hypertension is one of the most important determinants of micro- and macrovascular complications in patients with diabetes. Recent guidelines on treating hypertension in diabetes patients, based on clinical evidence of protection against target organ damage, especially as demonstrated by renal outcomes, recommended that office blood pressure (BP) be lowered to 130/80 mmHg in these patients.1 However, very few studies have consistently achieved BP levels as low as 130/80 mmHg in diabetic patients.

A landmark report related to the Action to Control Cardiovascular Risk in Diabetes (ACCORD) study showed that targeting a systolic BP of <120 mm Hg, as compared with <140 mm Hg, did not reduce the rate of a composite outcome of fatal and non-fatal major cardiovascular events in type 2 diabetics with at high risk for cardiovascular events.2 As a secondary outcome, intensive BP lowering was effective in reducing total stroke (P=0.01) and non-fatal stroke events (P=0.03).2 Although many observational studies support the ‘the lower, the better’ theory, it has not been clearly shown that the aggressive lowering of BP is indeed beneficial in the management of hypertension. The ACCORD study was a randomized control study that examined cardiovascular disease as an outcome. The extent of BP lowering in diabetes should be individualized by cardiovascular complications, microvascular complications and the severity of diabetes and hypertension. In the ACCORD subjects, 34% had experienced previous cardiovascular events, and 87% were on antihypertensive medications. The mean baseline BP was as low as 139/76 mmHg in all patients. It is not surprising that no benefit of a further reduction of BP was seen when targeting a systolic BP of <120 mm Hg. In the early stage of diabetes, aggressive control of risk factors could be effective for reducing cardiovascular outcomes.3, 4 In clinical practice, physicians occasionally hesitate to add antihypertensive medications to achieve clinic BP of 130/80 mmHg. The target BP level in patients with diabetes remains to be established. In terms of individualized BP control, ambulatory BP monitoring (ABPM) is the most useful tool for accurately evaluating BP level and variability.

For the assessment and management of BP, ABPM is better than clinic BP.5 ABPM can more reliably and easily assess actual BP levels than clinic BP and is helpful for predicting cardiovascular events, target organ damage and antihypertensive effects. Even in diabetes, we have shown that ambulatory BP levels more accurately predict future cardiovascular events.5 An abnormal dipping pattern has been established as a risk factor,6 and white-coat hypertension and masked hypertension have been shown to be moderate risk factors.7, 8 We showed that BP variability during sleep was a risk factor for cardiovascular disease even after adjusting for BP levels in patients with diabetes.9 Unless ABPM is performed, it is difficult to assess these measures and to perform detailed assessments, especially of nighttime BP. In the meantime, ABPM is not recommended for use in efforts that adhere to hypertension and diabetic guidelines because of the lack of a robust database related to ABPM in diabetes. However, there are increasing reports of the use of ABPM in diabetics, and we advocate that ABPM be performed at least once in all diabetic patients for the assessment and risk stratification of diabetes. An interesting paper recently published in the Journal of Hypertension reports that a daytime ambulatory BP of 129/79 mmHg and 134/88 mmHg corresponds to an office BP of 130/80 mmHg and 140/90 mmHg.10 However, as mentioned above, office BP and ambulatory BP do not always correspond.

In this issue of Hypertension Research, Gorostidi et al.,11 drawing on data from a Spanish database, describe patterns of ABPM in hypertensive patients with or without diabetes. The authors found that diabetic patients have higher BP levels and are more likely to be non-dippers; the riser pattern in particular was more frequent than in non-diabetic patients. This study is a descriptive study of ABPM using a large Spanish database, and the data represent a confirmation of previous findings. The strength of this study is the large size of the sample, representing data from as many as 68 045 ABPM records. This paper includes numerous information about the use of ABPM in patients with diabetes mellitus. The weakness of this study is that drug-related information was not described and that the database included subjects with a history of cardiovascular disease, which is associated with abnormal circadian BP patterns. Therefore, this study reflects a mixture of primary and secondary prevention with regard to BP management in diabetic patients. The subjects were extremely obese (body mass index 30.1±4.9 kg m−2), and the pathophysiology of diabetes would be somewhat different from that observed in Asian populations.

Diabetes mellitus is characterized by disordered homeostasis in terms of glucose and BP control. It has been shown that BP variation is associated with continuously monitored blood glucose. Such fluctuations in glucose and BP by themselves could increase the risk for target organ damage and could trigger vicious circles in diabetic patients. As was shown by our study, not only ambulatory BP levels5 but also autonomic nervous system disturbance, as evaluated by BP fluctuation at night, are risk indicators of cardiovascular outcomes.9 Nighttime BP in patients with diabetes was also important when assessed by home BP monitoring.12 At present, it has been proven that the riser pattern is extremely harmful.6 If this pattern is combined with a sleep disturbance such as short duration of sleep or disordered breathing during sleep, it could have a synergistic impact on the incidence of cardiovascular disease.13

Chronological therapy in diabetes is also important in patients with diabetes. Hermida et al.14 recently showed that antihypertensive drug therapy with at least one drug in the evening was more effective than a morning dosing schedule for lowering BP and reducing the likelihood of cardiovascular disease. Because patients with diabetes are salt sensitive, the use of diuretics for natriuresis is also important for controlling nighttime BP and could change the non-dipper pattern to a dipper pattern.15 Therefore, an antihypertensive treatment that takes into account circadian BP profile might be more effective than the conventional regimen in controlling BP in patients with diabetes. Because individualized therapy is important, ABPM should be performed at least once in all diabetic patients to achieve an improved cardiovascular prognosis.