Systolic blood pressure relates to the rate of decline of glomerular filtration rate in type II diabetes

Abstract

Objective: To relate deterioration in kidney function to some potential cardiovascular risk factors in type II diabetic patients.

Research design and methods: Twenty-four normoalbuminuric and 13 microalbuminuric patients completed a 3.4-yr prospective observational study. Glomerular filtration rate, urinary albumin excretion rate, blood pressure, glycemic control, and lipids were measured on entry and at the end of the study. Of the patients, 19 normoalbuminuric and 8 microalbuminuric (73%) patients had no history of antihypertensive treatment.

Results: The glomerular filtration rate was significantly reduced during the follow-up period (-1.34 +/- 0.54 ml.min-1.1.73 m-2 [mean +/- SE], P < 0.02). The rate of decline varied considerably in normoalbuminuric and microalbuminuric patients (from -13.5 to 4.3 and from -7.0 to 4.2 ml.min-1.1.73 m-2 per year, respectively) but was on average not accelerated in normoalbuminuric or microalbuminuric patients (-1.3 +/- 0.7 and -1.5 +/- 0.8 ml.min-1.1.73 m-2 per year, respectively). Significant correlations were observed between the glomerular filtration rate fall rate and initial systolic blood pressure (r = -0.47, P < 0.01; patients without antihypertensive treatment: r = -0.42, P = 0.03) but not diastolic blood pressure. In a stepwise multiple linear regression analysis, baseline systolic blood pressure significantly determined the fall rate of the glomerular filtration rate (regression coefficient = -0.050, SE = 0.018, P = 0.011; patients without antihypertensive treatment: regression coefficient = -0.047, SE = 0.021, P = 0.030).

Conclusions: In these type II diabetic patients neither normoalbuminuria nor microalbuminuria are at an average associated with an accelerated decline in kidney function. Still, systolic blood pressure is a determining factor for the rate of decline in the glomerular filtration rate. A longer follow-up time with consecutive glomerular filtration rate measurements are needed to determine the long-term implications of normoalbuminuria and microalbuminuria on kidney function in type II diabetic patients.