A 24-year-old black woman with a history of type 1 diabetes since age
12 had a urine albumin excretion of 175 mg over a period of 24 hours (microalbuminuric range, 30—300 mg) found on routine assessment. The patient was on a long-acting and regular insulin with poor compliance. Her glycosylated hemoglobin level ranged from 9% to 11%.
The patient had no family history of renal disease. Her blood pressure was 126/65 mm Hg sitting and 122/63 mm Hg standing. Her heart rate was 82 beats per minute and 76 beats per minute in the seated and standing positions, respectively. Her blood urea nitrogen level was 17 mg/dL and her serum creatinine level was 1.2 mg/dL. Dipstick urinalysis was negative for protein. A 24-hour urine collection indicated a glomerular filtration rate of 130 mL per minute.
Seven months later, the patient had an albumin excretion rate of 225 mg over a 24-hour period. At this time, 24-hour ambulatory blood pressure monitoring was done. During the daytime, her mean systolic and diastolic blood pressures were 119 mm Hg and 64 mm Hg, respectively. During
the sleep period, her mean systolic and diastolic blood pressures were
118 mm Hg and 62 mm Hg, respectively. The ratios of nighttime to daytime systolic and diastolic blood pressure were 0.99 and 0.97, respectively. Renoprotective therapy with an angiotensin-converting enzyme inhibitor was recommended. The patient was lost to follow-up until she was seen in our clinic 6 years later with overt proteinuria.
Although our patient’s office blood pressure was perfectly normotensive, her 24-hour ambulatory blood pressure showed a nighttime to daytime ratio above 0.9. This reflects a nondipping pattern, indicating nocturnal hypertension. If this pattern was present when she was normoalbuminuric, it could be inferred that this patient was at high risk of developing microalbuminuria.