Treating hypertension in the patient with overt diabetic nephropathy

Higher HDL cholesterol levels are associated with a lower incidence of chronic kidney disease in patients with type 2 diabetes

BACKGROUND AND AIMS

Type 2 diabetes is one of the most important risk factor for the development of chronic kidney disease (CKD). Recently, it has been shown that lower high-density lipoprotein cholesterol (HDL-C) levels predicted the development of microalbuminuria in type 2 diabetic individuals. We have prospectively assessed the effects of plasma HDL-C levels on the incidence of CKD in a large cohort of type 2 diabetic patients.

METHODS AND RESULTS

We followed 1987 type 2 diabetic outpatients with normal or near-normal kidney function at baseline for 5 years for the occurrence of incident CKD defined as glomerular filtration rate < or = 60 mL/min/1.73 m(2) (as estimated by the abbreviated Modified Diet and Renal Disease Study equation). Cox proportional hazards models were used to examine the independent relationship between plasma HDL-C levels and incident CKD. During a median follow-up of 5 years, 11.8% (n=234) of participants developed incident CKD. In multivariate regression analysis, higher HDL-C levels were associated with a lower risk of incident CKD (multiple-adjusted hazard ratio 0.76; 95% coefficient intervals 0.61-0.96; p=0.025) independently of age, gender, body mass index, hypertension, smoking history, diabetes duration, hemoglobin A1c, plasma triglycerides, LDL-cholesterol, presence of diabetic retinopathy, baseline albuminuria, and current use of medications (anti-hypertensive, anti-platelet, lipid-lowering and hypoglycemic drugs).

CONCLUSIONS

Higher plasma levels of HDL-C are associated with a lower risk of incident CKD in a large cohort of type 2 diabetic adults independently of numerous confounding factors.

Hypertension and diabetes: a toxic combination

OBJECTIVE

To assess the relationship of diabetes and hypertension and the effect on cardiovascular outcomes.

METHODS

A review of the English-language literature regarding the effects of diabetes and hypertension published between January 1, 1980, and April 30, 2008, was performed.

RESULTS

In type 2 diabetes, the prevalence of hypertension due to both hyperglycemia and insulin resistance is increased. High insulin levels are associated with left ventricular hypertrophy and decreased ventricular function. The growth factor effects of insulin on the myocardium are worsened by hypertension. The diabetic hypertensive patient is exquisitely sensitive to blood pressure lowering as it relates to cardiac events and mortality. Because of this, the blood pressure goals for diabetic hypertensive patients are lower than those for their nondiabetic hypertensive peers. Cardiac events have a stronger association with systolic hypertension and the pulse pressure than with diastolic hypertension. The presence of microalbuminuria not only signifies a higher risk of developing diabetic nephropathy, but also increased mortality and incidence of cardiovascular events. Thus, when microalbuminuria is detected, intensification of hypertensive therapies, especially suppression of the renin-angiotensin-aldosterone system, is essential.

CONCLUSION

The effects of hypertension in persons with diabetes increase the frequency and severity of cardiac events, especially when microalbuminuria is present.

Do pleiotropic effects of antihypertensive medications exist or is it all about the blood pressure?

Examination of the large-scale drug-versus-drug trials suggests that the initial drug choice is of token importance and that better blood pressure control is the primary determinant of superior outcomes. In pooled analyses, the achieved blood pressure is similar for older and less expensive drugs, such as thiazide-type diuretics, and for newer and more costly agents, such as angiotensin-converting enzyme inhibitors, -angiotensin-receptor blockers, and calcium-channel blockers. If blood pressure--independent differences favoring one antihypertensive drug class over another truly exist, they have been singularly difficult to uncover with any consistency. Considering that multidrug therapy is required in the majority of patients with hypertension, the debate as to which drug class is best to start with is moot, in that the clinician is now more called upon to decide the best combinations of drugs and not the best monotherapy.

The kidney and hypertension: causes and treatment

Chronic kidney disease is both a cause and a consequence of hypertension. Extracellular volume expansion is an important, if not the most important, contributing factor to hypertension seen in chronic kidney disease. Beyond volume expansion, chronic kidney disease-related hypertension is without truly defining characteristics. Consequently, the sequencing of antihypertensive medications for the patient with chronic kidney disease and hypertension becomes arbitrary. Prescription practice in such patients should be mindful of the need for multiple drug classes with at least one of them being a diuretic. Blood pressure goals in the patient with chronic kidney disease and hypertension are set at lower levels than those for patients with essential hypertension alone. It remains to be determined to what level blood pressure should be lowered in the patient with chronic kidney disease, however.

Increased risk of CKD among type 2 diabetics with nonalcoholic fatty liver disease

It is unknown whether chronic kidney disease (CKD) is associated with nonalcoholic fatty liver disease among patients with type 2 diabetes. We followed 1760 outpatients with type 2 diabetes and normal or near-normal kidney function and without overt proteinuria for 6.5 yr for the occurrence of CKD (defined as overt proteinuria and/or estimated GFR <60 ml/min per 1.73 m(2)). During follow-up, 547 participants developed incident CKD. Nonalcoholic fatty liver disease, diagnosed by liver ultrasound and exclusion of other common causes of chronic liver disease, was associated with a moderately increased risk for CKD (hazard ratio 1.69; 95% confidence interval 1.3 to 2.6; P < 0.001). Adjustments for gender, age, body mass index, waist circumference, BP, smoking, diabetes duration, glycosylated hemoglobin, lipids, baseline estimated GFR, microalbuminuria, and medications (hypoglycemic, lipid-lowering, antihypertensive, or antiplatelet drugs) did not appreciably attenuate this association (hazard ratio 1.49; 95% confidence interval 1.1 to 2.2; P < 0.01). In conclusion, our findings suggest that nonalcoholic fatty liver disease is associated with an increased incidence of CKD in individuals with type 2 diabetes, independent of numerous baseline confounding factors.