Can Metformin Cause High Blood Pressure

Can Metformin Cause High Blood Pressure?

Metformin is a widely used medication for managing type 2 diabetes mellitus (T2DM). Its effects on blood pressure (BP) have been the subject of various studies, with mixed results. This article synthesizes the findings from multiple research papers to address whether metformin can cause high blood pressure.

Metformin and Blood Pressure in Non-Diabetic Individuals

Several studies have investigated the impact of metformin on blood pressure in non-diabetic individuals. A randomized clinical trial involving hypertensive patients without diabetes found that metformin did not reduce blood pressure when compared to a placebo. Similarly, another study concluded that metformin did not decrease either 24-hour ambulatory or office blood pressure in non-diabetic, moderately obese, hypertensive patients. These findings suggest that metformin does not significantly affect blood pressure in non-diabetic individuals.

Metformin and Blood Pressure in Diabetic Models

In contrast, studies involving diabetic models have shown different results. Research on hypertensive diabetic db/db mice indicated that metformin normalized systolic blood pressure by reducing renal cathepsin B expression, which in turn affected sodium retention and blood pressure regulation. Additionally, metformin was found to alleviate salt-induced hypertension in spontaneously hypertensive rats, suggesting that it can blunt the rise in blood pressure caused by a high-salt diet.

Metformin and Insulin Sensitivity

The relationship between metformin, insulin sensitivity, and blood pressure has also been explored. In a study using fructose-fed hyperinsulinemic, hypertensive rats, metformin treatment prevented the increase in both plasma insulin levels and systolic blood pressure. This indicates that metformin's ability to improve insulin sensitivity may contribute to its antihypertensive effects in certain contexts.

Metformin and Postprandial Blood Pressure

Metformin has also been shown to modulate postprandial blood pressure. In patients with type 2 diabetes, metformin attenuated the fall in systolic blood pressure following oral glucose intake, which is often inadequately compensated in these patients. This suggests that metformin may help regulate postprandial blood pressure, potentially contributing to its favorable cardiovascular profile.

Adverse Effects on Orthostatic Blood Pressure

However, not all findings are positive. A study from the Copenhagen Insulin and Metformin Therapy (CIMT) trial indicated that metformin might adversely affect orthostatic blood pressure recovery in patients with type 2 diabetes. The study found an increased early drop in orthostatic blood pressure in the metformin group compared to the placebo group, suggesting a potential adverse effect on cardiovascular autonomic neuropathy.

Meta-Analysis Findings

A meta-analysis of randomized controlled trials evaluated the effects of metformin on systolic and diastolic blood pressure in non-diabetic patients. The analysis found that metformin had a significant effect on reducing systolic blood pressure, particularly in patients with impaired glucose tolerance or obesity, but did not significantly affect diastolic blood pressure.

Conclusion

In summary, the evidence suggests that metformin does not cause high blood pressure. In non-diabetic individuals, metformin appears to have no significant effect on blood pressure. In diabetic models and certain hypertensive conditions, metformin may even help lower blood pressure. However, there are some contexts, such as orthostatic blood pressure recovery, where metformin might have adverse effects. Overall, metformin's impact on blood pressure is complex and context-dependent, but it does not appear to be a cause of high blood pressure.

Summary

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