Diabetes Care, Vol 20, Issue 5 859-863, Copyright © 1997 by American Diabetes Association
White coat hypertension in NIDDM patients with and without incipient and overt diabetic nephropathy
FS Nielsen, P Gaede, P Vedel, O Pedersen and HH Parving
Steno Diabetes Center, Gentofte, Denmark.
OBJECTIVE: Early data have suggested a high prevalence of white coat
hypertension (approximately 50%) in NIDDM patients. To study this
phenomenon further, we determined the prevalence of white coat hypertension
in NIDDM patients with normo- or microalbuminuria or with diabetic
nephropathy. RESEARCH DESIGN AND METHODS: Three groups of hypertensive
NIDDM patients (repeated clinic blood pressure > 140/90 mmHg or
antihypertensive treatment) attending the Steno Diabetes Center were
investigated in a cross-sectional study. Group 1 had normoalbuminuria (a
urinary albumin excretion [UAE] rate < 30 mg/24 h, n = 30, age 61 +/- 7
[mean +/- SD] years, 20 men), group 2 had microalbuminuria (UAE rate 30-300
mg/24 h, n = 51, age 55 +/- 7 years, 35 men), and group 3 had diabetic
nephropathy (UAE rate > 300 mg/24 h, n = 47, 62 +/- 7 years, 36 men). If
given, all previous antihypertensive medication was withdrawn at least 2
weeks before the study (48%). The prevalence of white coat hypertension
(clinic hypertension with normal blood pressure values at home) was
determined by comparison of clinic blood pressure (Hawksley Random
sphygmomanometer) and the ambulatory daytime (7:00 A.M. to 11:00 P.M.)
blood pressure (A&D TM2420). By applying established criteria, white
coat hypertension was confirmed if daytime blood pressure was < 135/85
mmHg. RESULTS: The clinic blood pressure was 155/86 (SE 3/2) mmHg, 156/89
(2/1) mmHg, and 171/90 (3/2) mmHg in group 1, 2, and 3, respectively (P
< 0.05 comparing group 3 with groups 1 and 2). The prevalence of white
coat hypertension was significantly higher in group 1 as compared with
groups 2 and 3, 23% (95% CI 10-42) vs. 8% (2-19) and 9% (2-20) (P <
0.05), with no difference between the latter two groups. CONCLUSIONS: The
prevalence of white coat hypertension in normoalbuminuric NIDDM patients
resembles that observed in nondiabetic subjects with essential
hypertension, whereas the prevalence is significantly lower in NIDDM
patients with incipient or overt diabetic nephropathy, suggesting a
difference between primary and secondary hypertension.