Understanding the Haemodynamic Theory of Diabetic Complications

Diabetes is a complex disease that can lead to severe complications, particularly affecting the microvascular system. One significant aspect of these complications is hypertension, which may play a more substantial role in their progression than hyperglycaemia itself, especially once complications are already present. The haemodynamic theory sheds light on how blood flow dynamics contribute to these microvascular issues.

According to this theory, hyperglycaemia exerts an osmotic effect that disrupts the normal autoregulatory mechanisms in tissues, leading to increased blood flow that can exacerbate tissue damage. Over time, chronic abnormalities in blood flow through capillary beds can result in microvascular complications. For instance, retinopathy, a common diabetic complication affecting the eyes, is often less severe in patients with carotid artery stenosis, which limits downstream blood pressure, supporting the notion that blood flow regulation is crucial.

Research indicates that aggressive management of blood pressure, targeting values below 120–130/80 mmHg, can significantly slow the progression of these microvascular complications. Furthermore, smoking has been identified as a risk factor that can worsen diabetic complications, potentially due to its detrimental effects on vascular function.

Another key player in this scenario is the renin-angiotensin system (RAS). Blockade of this system through medications such as angiotensin-converting enzyme (ACE) inhibitors or angiotensin receptor blockers has been shown to slow the progression of microvascular complications more effectively than other blood pressure-lowering treatments. This protective effect is particularly notable in nephropathy, with emerging evidence also supporting benefits for retinopathy.

In addition to hypertension and the renin-angiotensin system, the growth hormone-insulin-like growth factor (GH–IGF) axis has been implicated in the development of microvascular complications. Historical cases, such as a woman with type 1 diabetes experiencing diabetic retinopathy, suggest a complex interplay between hormonal regulation and vascular health.

Understanding these mechanisms is essential for better management of diabetes and its complications. By focusing on blood pressure control and the modulation of specific hormonal pathways, healthcare providers can develop more effective strategies to mitigate the risks associated with diabetic microvascular complications.