Hypertension and Diabetes

Hypertension is a common finding in the diabetic patient. In Type 1 diabetes (IDDM) hypertension usually develops after renal impairment. The hypertension subsequently accelerates the decrease in renal function. Type 2 diabetes (NIDDM), the adult and most common type of diabetes, is associated with obesity. In fact, obesity is involved in the pathogenesis of Type 2 diabetes. The alarming increase in diabetes worldwide coincides with the increased prevalence of obesity.

This combination of diabetes and hypertension is lethal to the cardiovascular system. Strokes, myocardial infarctions, heart failure, and renal failure are all increased in the diabetic patient with hypertension. However, the benefits of treatment are even greater than the benefits of treatment of the non-diabetic hypertensive patient. All studies have emphasized this greater benefit. It appears that the higher the risk the greater the benefit from treatment of hypertension. The benefit is also related to the degree of hypertension control. In the United Kingdom Prospective Diabetes Study (UKPDS) 1"tight" but still not optimal control of blood pressure (mean 144/82 mmHg) compared with usual treatment (154/87 mmHg) resulted in a 24% reduction in any diabetic complication and a 32% reduction in deaths related to diabetes, primarily myocardial infarctions and strokes. Patients who also had good glucose control had even fewer complications.

The Sixth Report of the Joint National Committee on Detection, Evaluation and Treatment of High Blood Pressure (JNC VI) set 130/85 mmHg as the treatment goal for hypertensive diabetic patients and as low as 125/75 mmHg for patients with renal insufficiency with proteinuria greater than 1 gram/24 hours. The treatment goal should begin with lifestyle changes, particularly weight reduction in Type 2 diabetes. Weight loss can improve glucose, lipid and blood pressure control. The presence of diabetes, a major risk factor, demands the institution of drug therapy.

Which drug should be started? This is not easy to answer, but one principle to remember is that control of blood pressure is the critical goal and this usually requires two to three drugs. In patients with diabetic nephropathy an ACE inhibitor should be one of the drugs. In patients with angina or a recent myocardial infarction b -blockers should be used. The concern over hypoglycemia with the use of b -blockers has been grossly exaggerated. b -blockers have clearly been shown to save lives post myocardial infarction.

Usually, the management of the hypertensive diabetic patient involves a three-prong approach:
  1. control of blood pressure
  2. control of glucose and
  3. control of lipids.
The middle-aged or older diabetic patient is assumed to have underlying coronary heart disease. The dyslipidemia should be vigorously treated to reduce the LDL cholesterol below 100 mg/dl. Glycemic control can also improve abnormal lipid levels, especially triglycerides.

This vigorous treatment of the hypertensive diabetic patient can yield gratifying results in lowering cardiovascular complications, but it is expensive and beyond the reach of many developing countries. However, even small decreases in blood pressure can reduce complications, so do something!

An action that can have a profound long-term effect on the cardiovascular disease rate in a country is PREVENTION: PREVENTION OF OBESITY, the central risk factor that links hypertension – diabetes – dyslipidemia. The key to success is to control obesity at an early age.

Reference
  1. UK Prospective Diabetes Study (UKPDS) Group. Tight blood pressure control and risk of macrovascular and microvascular complications in type 2 diabetes. UKPDS 38. BMJ 317: 703-713, 1998.
Patrick J. Mulrow, M.D.
Secretary General
World Hypertension League
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