Luis M Ruilope, MD, and Anna Solini, MD, PhD, presented a pro/con argument article in the May 2011 edition of Diabetes Care. They were tackling the question of whether renin-angiotensin system (RAS) inhibitors should be used in every patient with type 1 diabetes or type 2 diabetes. The suggestion that this could be done comes from the known role of RAS blockade in blood pressure regulation and organ protection.
The counter argument to this is that RAS inhibitors should not necessarily be used in every patient; there could be better options for achieving the same goal, including calcium-channel blockers—alone or in combination with ACE inhibitors.
The arguments will be summarized here.
Lowering albuminuria using RAS inhibitors also protects the cardiovascular system (as shown by the Losartan Inteventaion For Endpoint reduction in hypertension [LIFE] study, as well as in the Reduction of End Points in Type 2 Diabetes With the Angiotensin II Antagonist Losartan [RENAAL] study).
Additionally, it should be pointed out that the ethnicity of the patient needs to be taken into account when beginning an antihypertensive therapy. The Antihypertensive and Lipid-Lowering Treatment to Prevent Heart Attack Trial (ALLHAT) study and LIFE study showed that a diuretic-based therapy is better than an RAS suppressor for black hypertensive patients without renal disease or heart failure.
It can be said that RAS inhibitors provide nephroprotection--better than other antihypertensive agents--but there isn’t evidence to be able to say that they provide better cardioprotection.
Commentary by Colleen Flynn MD
The most important aspect of blood pressure control in patients with diabetes is actually lowering the blood pressure to goal. Most physicians will reflexively place a diabetic patient on a RAS-inhibitor at the first sign of hypertension. However, the first step should be measuring kidney function and albuminuria.
Microalbuminuria (30-300 mcg/mg) is not a surrogate for diabetic nephropathy, but rather a marker of inflammation. Other causes of microabluminuria include poor glucose control, poorly controlled blood pressure, elevated cholesterol, a high salt diet, and infection. Physicians should address these other etiologies of microalbuminuria and monitor for improvement.
Rather than assuming the patient has early signs of diabetic nephropathy and automatically treating with a RAS blocker, patients should be assessed for other causes of microalbuminuria. If a diabetic patient has macroalbuminuria (>300 mcg/mg), then there is an indication to treat with an ACE or ARB.