March 19, 2001
Complications
Question from Madison, Wisconsin, USA:
I am 34 years old and have had type�1 diabetes since age eight. Over the past two years, since beginning to use an insulin pump, my hemoglobin A1c results have all been under 6.5% (normal lab values 4.6-6.1%), but prior to that time, they were far more erratic and usually hovered in the 8-9% range and regularly remained above that during my adolescence. I am not hypertensive, I do not smoke, and my diet is low in protein intake.
Over the past two years, my levels of microalbumin have been 13 and 12. The first value was from a 24 hour urine collection and the second from a random sample. While these values are beyond the normal limits according to lab values, they are not clinically at levels of microalbuminuria (which I understand to be 20). I have a few questions:
Are these elevated values indicative of an irreversible course toward diabetic nephropathy?
Are there any studies that demonstrate that it is possible to reverse these abnormal levels?
An answer to a previous question stated that there is no evidence to support treatment with ACE inhibitors prior to the development of microalbuminuria. Therefore, ACE inhibitors are not routinely prescribed for patients with normal albumin excretion rates. However, my values are clearly not in the normal range. Are there any data that indicate that treatment with ACE inhibitors at this stage would be beneficial?
Answer:
As things stand now, we do not have data from large prospective patient trials which clearly indicate benefit from ACE inhibitor therapy when the microalbumin excretion rate is in the normal range. These studies are currently under way. However, you would like to extrapolate to your situation.
To do that, I would suggest serial measurement of microalbumin excretion, and, if you see a trend upward into the high normal range, I think that ACE inhibitor therapy would be reasonable. The institution of the medication can normalize microalbumin excretion (or make it lower in this case). Data does exist to suggest that patients with microalbuminuria have stabilization of their kidney function, in terms of albumin excretion and filtration function. Therefore, I would not generalize to the point of saying your numbers are going to lead to a continuous worsening of kidney function.
Although we think microalbuminuria is an indicator of risk of developing nephropathy, it turns out that it is not quite as predictive as we once thought. Put ACE inhibitors into the picture and there is good reason for optimism. Besides you have already had diabetes for over 20 years — you have managed to avoid the development of nephropathy during the high risk period.
JTL
