Hypertension in Diabetes

Hans Tandra - 2004

Diabetes mellitus and hypertension are both major public health problems that co-exist frequently, associated with a significant morbidity and mortality. Both occur in increasing frequency with increasing age and they have a common predisposing factor, i.e. insulin resistance.
In type 2 diabetes, hypertension may be present before the diagnosis of diabetes or at the time of diagnosis. In contrast, in type1 diabetes, hypertension is usually related to diabetic nephropathy.
The presence of hypertension in diabetic patients increases the mortality 4-5 folds largely through coronary artery diseased and stroke.

Hypertension may also be an aetiological factor in diabetic nephropathy and retinopathy. Hence treatment of hypertension in a diabetic has considerable therapeutic advantage and should be carried out vigorously. In the choice of antihypertensive agents one must consider the potential impact of the treatment on the metabolic disorder.

Epidemiology

The reported prevalence of hypertension in diabetes varies widely, but is probably 2 times higher than that reported in the general population.
In the United States, nearly one in four adults has hypertension, and more than 10 million adults have diabetes. As many as 35-50% of European diabetic population aged 35-50 years may be hypertensive with even higher frequency in women.
Hypertensive patients show an increased prevalence of impaired glucose tolerance (IGT) or non-insulin dependent diabetes mellitus (NIDDM), sometimes when they are diagnosed as hypertensives but more often subsequently, possibly in part because of diabetogenicity of certain antihypertensive drugs.

Etiology of Hypertension in Diabetes

ypertension is common among diabetics and has the same pathogenetic mechanisms as insulin resistance, in which the activated renin-angiotensin system contributes to the emerging high blood pressure and hyperglycemia. Hyperglycemia is one of the triggering factors for vascular dysfunction and clotting abnormalities and, therefore, for accelerated atherosclerosis in diabetes. Glycated hemoglobin levels, as a reflection of the degree of glycemia, are strongly associated with the risk of cardiovascular disease in diabetics and in the general population.

The various types of hypertension which occur in patients with diabetes mellitus are:

1. Hypertension associated with NIDDM, insulin resistance, and hyperlipidemia, syndrome X
2. Hypertension associated with intensified insulin treatment
3. Coincidental hypertension in diabetic patients
4. Essential hypertension
5. Isolated systolic hypertension
6. Secondary hypertension in diabetes

• endocrine diseases causing both hypertension and diabetes: acromegaly, Cusshing’s syndrome, Conn’s syndrome, pheochromocytoma
• drugs causing both hypertension and diabetes: oral contraceptives (combine preparation), glucocorticoids
• antihypertensive drugs causing diabetes: potassium-losing diuretics (especially chlorthalidone), b-blockers, diazoxide
• hypersion secondary to diabetic complications: nephropathy, renal scarring following recurrent urinary tract infections, isolated systolic hypertension due to atherosclerosis.