Abstract
Background: Normal circadian blood pressure response includes a nocturnal fall in BP by 10 to 20% of the average daytime BP. Many diseases, including diabetes mellitus, alter these normal circadian BP changes. DM, through its long-term microvascular and macrovascular complications, such as autonomic neuropathy, affects BP dipping patterns by decreasing dipping (non-dipper), exaggerating dipping (nocturnal hypotension), or causing an actual increase in BP (reverse dipping). These altered dipping patterns are likely to be more common in those with long-standing hyperglycemia, poor glycemic control, and concurrent renal dysfunction. Abnormal dipping patterns (non-dipping and reverse dipping) are associated with increased target organ damage and cardiovascular risk among diabetic patients. The BP variation and dipping patterns are best studied using ambulatory blood pressure monitoring. This study has compared BP dipping patterns in patients with T2DM and healthy controls and evaluated their correlation with the duration of diabetes, glycemic status, and renal status by employing Ambulatory Blood Pressure Monitoring (ABPM).
Materials and Methods: 50 patients with T2DM for more than 5 years have been compared with 50 normal subjects (controls) for alteration in the circadian BP pattern and its relationship with the patients’ duration of diabetes, glycemic status, and renal status.
Results: This study has revealed statistically significant findings concerning abnormal dipping patterns (non-dipping and reverse dipping) between diabetic and non-diabetic patients (56% vs. 24%, p-value=0.001), between the duration of diabetes for more than 10 years and 5-10 years (77.8% vs. 43.8%, P=0.02), between higher HbA1c of more than 9% and 7-9% (34.5% vs. 4.8%, P=0.0001), between patients with proteinuria and those without proteinuria (p=0.045), and between patients with microalbuminuria and those with no microalbuminuria (87.5% vs. 41.2%, p=0.002).
Conclusion: Compared to normal subjects, most patients with T2DM had an abnormal BP dipping pattern. The duration of DM, poor glycemic control, and renal dysfunction (proteinuria and microalbuminuria) were positively correlated with nocturnal BP dipping pattern abnormalities.
Keywords: Dipping pattern of BP, Non-dippers, Reverse dippers, Type 2 diabetes mellitus, Ambulatory blood pressure monitoring, Duration of DM, Glycemic control, Renal status.