Characteristics and prognosis of normoalbuminuric type 1 diabetic patients

Intervention in type 1 diabetic patients with increased urinary albumin exc retion (UAE) represents a great step forward in modem diabetology. At the m oment, the consensus calls for anti-hypertensive treatment in normotensive type 1 diabetic patients with persistent microalbuminuria. However, recent data indicate chat substantial pathophysiological changes have already take n place at the microalbuminuric stage. Thus, prevention of progression from normo- to microalbuminuria would be a major clinical turning point. A cons iderable number of potential risk factors for progression to microalbuminur ia have been proposed, among which are blood pressure elevation and disturb ancies in circadian blood pressure variation. We performed 24-h ambulatory blood pressure (AMBP) monitoring in 115 normoalbuminuric (UAE <20 mu g/min) patients, along with performing an assessment of circadian blood pressure and heart rate (HR) variation and a short-term power spectral analysis of R R interval oscillations. Patients with UAE above the median had significant ly higher systolic and diastolic AMBP compared to the low nonnoalbuminuric group. The difference in blood pressure between the two groups was most pro nounced for the night blood pressure (P < 0.01 and 0.02). A positive correl ation between UAE and circadian variation (described as diastolic night/day ratio) was present-that is, the higher the normoalbuminuria, the more blun ted the night/day ratio. The patients characterized by a combination of hig h-normal UAE and blunted circadian variation also proved to have significan tly higher HbA(1c) values, higher 24-h mean arterial blood pressure, and lo wer vagal activity. In conclusion, high normal UAE, poor metabolic control, and cigarette smoking are: at present the only established risk factors fo r progression from normo- to microalbuminuria. However, new data emphasizes the close relation between blood pressure and albumin excretion. Pathophys iological abnormalities (poorer glycemic control, higher blood pressure, an d attenuated vagal activity) tend to cluster in patients characterized by h igh-normal UAE and blunted circadian variation of blood pressures, and this patient group might constitute a putative high-risk group.