Hypertension Aad Diabetes: The Bad Companionship

Hypertension Aad Diabetes: The Bad Companionship
Prof. Dr. Tarek El Baz, MD Prof. of Internal of Medicine & Nephrology _ Azhar University Hypertension Aad Diabetes: The Bad Companionship
INTRODUCTON
Hypertension complicates diabetes in all populations and occurs with increasing frequency with advancing age.
Both disorders are potent independent risk factors for cardiovascular, cerebral, renal, and peripheral atherosclerotic vascular disease.
It is estimated that 30-75% of diabetic complications can be attributed to hypertension, which is approximately twice as common in diabetic patients as in non diabetics.
In order to emphasize the importance of detection & management of hypertension in diabetes, the following questions should be addressed:
1. What is the epidemiology of hypertension in diabetes?
2. What is the relationship between hypertension & diabetic vasculopathy?
3. What is the pathophysiology of hypertension in diabetes?
4. What are the therapeutic goals of treatment?
5. What drugs to use, & what can be accomplished by treatment?
Question 1:
What is the epidemiolgy of hypertension in diabetes‘?
Differences in natural history are present between type 1& type 2 DM. For type 1 DM, patients are normotensive at the presentation of diabetes & remain so for 5-10 y. the occurrence of hypertension thereafter is in concert with the onset of nephropathy.
Conversely type 1 diabetics for >30 y without nephropathy are rarely found to be hypertensive.
In contrast, type 2 DM patients are frequently hypertensive at the time of diagnosis.
This suggests a common underlying mechanism for both diseases to occur together.
This group of patients is found to share common risk factors such as obesity & insulin resistance, also other components of the metabolic syndrome may coexist.
Question 2:
What is the relationship between hypertension & diabetic vascoulopthy?
The risk of diabetic vasculopathy is greater in the presence of hypertension, & this implies for both micro & macrovascular complications.
Diabetes is regarded as a major risk factor for the occurrence of stroke whether in men or women doubling the incidence over that of the non diabetic population.
Hypertension per se increases the risk of stroke to six folds in the general population. Thus the impact of hypertension on diabetes favors a substantial increase in the incidence of stroke.
Diabetes is also an independent risk factor for coronary heart disease, and again the risk is doubled in association with hypertension. Prof. Dr. Tarek El Baz, MD
Prof. of Internal of Medicine & Nephrology _ Azhar University
Hypertension Aad Diabetes: The Bad Companionship
Hypertension beyond doubt helps in progression of diabetic nephropathy, and increase the risk of retinopathy.
Hypertensive‘ diabetics are also at a greater risk for the development of peripheral vascular disorders that may end by amputations.
Question 3 :
Whit is the plthophysiology of hypertension in diabetes?
There seems to be a multiplidty of factors that interplay, thus underlying the association of hypertension & diabetes.
Hypertension in diabetes is recognized to be associated with an expanded plasma volume, an increased peripheral resistance &alow plasma renn in activity.
These facts are evidenced by the occurrence of hypertension with high levels of hyperglycemia that increases the osmolality of the extracellular fluid.
Secondly exchangeable sodium increases in the face of hyperglycemia leading to a vascular volurne expansion.
The low plasma rennin activity noticed in hypertensive diabetics was found to be due to the increased extracellular volume & an impaired synthesis and release of rennin from JCA. There also seems to be an important role for insulin resistance & hyperinsulinernia in the pathogensis of hypertension in diabetes. Firstly, insulin stimulates renal sodium retention, predisposing to volume overload.
Secondly, insulin stimulates carbohydrate metabolism leading to activation of adrenergic activity, which would reflect on the occurrence of peripheral vasoconstriction.
But other factors must also be operative, since the fact that, not all hyperinsulinemic diabetics develop hypertension.
One of these other possible factors is the inherited increase in the sodium lithium countertransport activity.
Question 4 :
What are the therapeutic goals of treatment?
The goal of treating hypertension in diabetic patients should be to prevent death & disability associated with high blood pressure, with the least disturbance to the quality of life.
ln addition other reversible risk factors for cardiovascular disease need to be addressed. The optimal blood pressure in diabetics is unknown. According to the Fifth Report of the joint National committee on Detection, Evaluation, and Treatment of high Blood Pressure (JNC-V), in non diabetic patients, nonfatal and fatal cardiovascular diseases including coronary heart disease, stroke, renal disease and all cause mortality, increases progressively with higher levels of both systolic & diastolic blood pressure.
ln the general population, risks are lowest for adults with an average systolic blood pressure The JNC-V defines hypertension as an average blood pressure of > 140 mmHg systolic or>90 mmHg diastolic.
As a general rule in treating hypertensive diabetics, the lower the better apart from orthostatic hypotension.
In general targets would aim at Question 5 :
What drugs to use, and what can be aoccmplished by treatment?
Early treatment of hypertension is particularly important in diabetic patients both to prevent cardiovascular disease and to progression of renal disease and diabetic retinopathy.
Among type 2 DM patients, the benefits of tight blood pressure control may be as great or greater than the benefit of strict glycernic control.
Therapy is of two components, that will be discussed in the following:
1.LIFE STYLE MODIFICATIONS
With certainty life style modifications are the foundation of diabetic & hypertension management.
They may be definitive treatment or adjunctive to pharmacological therapy.
These include weight management, nutrient modifications, increased physical activity, moderation of alcohol ingestion, and smoking cessation.
In addition to reducing hyperglycemia & hypertension, life style modifications have the added benefit of reducing the associated dyslipidemia.
2. PHARMACOLOGICAL TREATMENT OF HYPERTENSION
(A detail of the mega trials addressing this aspect has been published in last months issue, Comprehensive Prevention & Therapy of Diabetic nephropathy).
Intensive drug therapy is unequivocally protective.
All diabetic patients should therefore have their blood pressure lowered to below 130/85 mmHg.
ANGIOTENSIN CONVERTING ENZYME INHIBITORS ACEI
They lower blood pressure although they are not effective as monotherapy, they are lipid neutral & may lower plasma glucose concentration by increasing responsiveness to insulin, they also offer renoprotective effects due to lowering of intraglomerular pressure & through other mechanisms.
Based on the results of the HOPE trial, the FDA has approved the use of Ramipril for the reduction of MI, stroke, and cardiovascular and all -cause mortality in high risk patients including diabetics.
ANGIOTENSIN ıı RECEPTOR BLOCKERS ARBS
The beneficial effects of ACE inhibitors, have been illustrated in slowing the progression of diabetic nephropathy in type 1 DM.
This was less apparent for type 2 DM individuals.
There are more data currently available on the efficacy of ARBs in this setting.
The RENAAL study, demonstrated a clear benefit in terms of renoprotection using Losartan in patients with variable degrees of diabetic nephropathy.
diuretics
Dietary salt restriction and diuretics are likely to be effective in hypertensive diabetics.
Salt restriction reduces the blood pressure in most patients, at least in part by reversing the underlying tendency to volume expansion.
Metabolic complications and a possible increase in cardiovascular risk have been a major issue.
It is likely that these issues are avoided with low dose therapy, such as 12.5-25 mg of hydrochlorothiazide.
CALCIUM CHANNEL BLOCKERS CCB
Somewhat similar considerations (efficacy and lack of adverse effects of lipid or carbohydrate metabolism) apply to the nonhydropyridine calcium channel blockers (dilitiazem & verapamil), although there long term effect on diabetic nephropathy remains to be determined.
Although the ABCD trial showed adverse cardiovascular effects when CCB were used to treat hypertensive diabetics, the HOT trial denounced that finding which was probably secondary to the absence of a cardioprotective effect of the ACE used in the second arm of the ABCD trial.
AIPHA ADRENGIC BLOCKERS
Although not widly used as a primary therapy in diabetics because of orthostatic hypotension, they are still quite effective in lowering blood pressure and are also lipid neutral.
However, the ALLHAT trial, discontinued the doxazosin treatment arm because of the higher incidence of congestive heart failure.
BETA blockers
are effective drugs in controlling hypertension in diabetics.
The UKPDS showed that atenolol was as effective as captopril in terms of blood pressure control and protection from microvascular disease.
Carvedilol is a combined nonselective beta and alpha blocker, that improves survival in patients with congestive heart failure, and certainly has advantages over other beta blockers in patients with diabetes.
it’s used in diabetics was associated with a 20 % increase in glucose disposal, an 8 % reduction in plasma insulin levels and a 20 % reduction in serum triglycerides.
RECOMMENDATIONS
The optimal initial agent to be used in a hypertensive diabetic would be an ACEi.
However in terms of renoprotection an ARBs would be needed in a type 2 DM, with overt nephropathy.
Second line would be a low dose of hydrochlorothiazide.
lf targets are still not reached a choice between a beta blocker or a nonhydropyridine CCB is left to physician’s choice according the clinical status of the patient.