Nocturnal blood pressure is associated with the progression of microvascular complications and hypertension in patients with type 1 diabetes mellitus

Abstract

Aims

To evaluate relationships between early alterations in blood pressure and the progression of microvascular complications of diabetes in clinically-normotensive patients with type 1 diabetes (T1DM).

Methods

In a prospective observational study of 85 normotensive T1DM patients without microalbuminuria, blood pressure (BP) was monitored over 24 h using the ambulatory blood pressure monitoring (ABPM) system at baseline and 7 years later. Development or progression of microalbuminuria, retinopathy and hypertension was evaluated.

Results

Initially, 20 patients (24%) were diagnosed with masked hypertension and 31 (37%) with non-dipper pattern as the only pathological findings. At 7 years: 1) twenty-seven patients (32%) had progression of retinopathy related to the nocturnal diastolic blood pressure (BP_D) (OR:1.122; p = 0.034) and final non-dipper pattern (OR:5.857; p = 0.005); 2) seven patients (10%) developed microalbuminuria for which nocturnal systolic blood pressure (BP_S) was a risk factor (OR:1.129; p = 0.007); 3) five of the normotensive patients (9%) progressed to hypertension; historic HbA1c (OR:2.767; p = 0.046) and nocturnal BP_D (OR:1.243; p = 0.046) being the related risk factors. BP_D level ≥ 65 mmHg was associated with an increase in progression of retinopathy and hypertension.

Conclusions

In T1DM patients there is an elevated prevalence of BP alterations, detected using ABPM. Alterations in nocturnal BP predispose to development/progression of microvascular complications and overt hypertension.

Introduction

In patients with type 1 diabetes (T1DM), the presence of hypertension (HT) is considered one of the principal factors for the development and progression of microvascular complications (Rodrigues, Canani, Schvartzman, & Gross, 2011) such as nephropathy (Chillarón et al., 2013) and retinopathy (Hammes et al., 2011), as well as cardiovascular disease (Bild and Teutsch, 1987, Miller et al., 2013). Several intervention studies have demonstrated the benefit of BP control not only in patients with diabetes but also in the general population (Heart Outcomes Prevention Evaluation Study Investigators, 2000, Patel and ADVANCE Collaborative Group, 2007).

It is becoming progressively more usual to employ ambulatory blood pressure monitoring (ABPM). The technique has better reproducibility, reduces the patient's alarm or “white coat hypertension” and whose results correlate better with target organ involvement and cardiovascular morbid-mortality (Bliziotis et al., 2012, Gaborieau et al., 2008). Further, it enables the detection of subclinical alterations of blood pressure (BP), such as the circadian rhythm alteration and/or the presence of masked hypertension (Pickering, Shimbo, & Haas, 2006). These alterations can be missed when isolated BP measurements are made, and are more prevalent in patients with diabetes than in the general population (Chatterjee et al., 2009, Darcan et al., 2006, Flores et al., 2000, Lurbe et al., 2001). Our group observed (Vílchez-López et al., 2011) an elevated prevalence of masked hypertension [up to 32% presented with pathological average systolic (BP_S) or diastolic (BP_D) values during activity period] and the non-dipper pattern in 42% of patients with T1DM who were normotensive based on single measurement of BP. These findings were related to the deterioration of metabolic control and an atherogenic lipid profile.

Despite there being considerable evidence that the coexistence of hypertension and diabetes increases the risk of development and progression of chronic complications (Bild and Teutsch, 1987, De Boer et al., 2008), there is insufficient information on the role of subclinical blood pressure alterations in relation to the progression of microangiopathy complications in diabetes, and on the development of overt HT.

The objective of the present study was to evaluate the relationships between the presence of early subclinical BP alterations (detected using ABPM) and the progression of retinopathy, the development of microalbuminuria and the appearance of overt HT in clinically-normotensive T1DM patients.