Only a fraction of persons with Type 1 diabetes (less than 40%) develop diabetic kidney disease (nephropathy). When the urinary albumin (a protein normally excreted in small amounts) is within the normal range, the prevalence of high blood pressure (hypertension) based on office blood pressure readings is very low. Many of these persons, however, develop nocturnal hypertension (high nighttime blood pressure) before the development of abnormally high urinary albumin excretion (a condition referred to as microalbuminuria). Currently, early treatment with medications called ACE inhibitors is only recommended after there is an indication of kidney damage, as reflected by the presence of microalbuminuria. Beginning ACE inhibitor therapy is currently not recommended prior to the development of microalbuminuria, unless patients have high blood pressure, because it would result in over-treatment of many people. By the time that microalbuminuria develops, however, kidney damage may be present and many patients will develop kidney disease. It would therefore be beneficial to identify those subjects who will develop microalbuminuria, so that treatment could be started early for those individuals. Persons who may go on to develop protein in their urine and eventual kidney disease perhaps could be identified on the basis of an abnormal fall (too little) in blood pressure at night. This pattern should not be confused with high blood pressure, but instead seen as an early indication present before the development of high blood pressure and microalbuminuria.