I am interested in learning more about microvascular complications (especially kidney) in kids under age 7 diagnosed with Type 1 diabetes. Is it true that until after puberty that these complications don't really seem to kick-in for the kids? After puberty, what percentage of the children will go on to develop these complications?
If I read the DCCT notes correctly, these complications can be either significantly (>80%) reduced or averted if stringent control is maintained. What exactly is acceptable control for children (e.g., blood glucose in the range of 80-180, or should it be even tighter still)?
I have a friend of a friend (who is Type 1) who was in the hospital during the last 6 months of her pregnancy due to her diabetes and is now in kidney distress that was attributed to the pregnancy. Does being pregnant really affect diabetics that drastically or do you suppose there was some underlying cause for her problems. She is now 45 and gave birth 12 years ago and has been diabetic since youth.
The DCCT study did show that strict control of the blood sugar can decrease the risk of early complications. The study was not carried out long enough to prove if or how much strict control could decrease the risk of late, severe complications such as blindness or kidney failure, though it seems reasonable to assume that strict control will help prevent or delay these more serious complications.
In the initial report "The effect of intensive treatment of diabetes on the development and progression of long-term complications in insulin-dependent diabetes mellitus" in the New England Journal of Medicine, September 30, 1993, volume 329, pages 977-86, the development of complications was expressed as "rate of event per 100 patient years." ("Patient years" is the number of patients followed multiplied by the number of years they are followed. "100 patient years" can equal 100 patients followed for 1 year, or 50 patients followed for 2 years, 25 patients followed for 2 years plus 50 patients followed for 1 year, 10 patients followed for 4 years, 10 patients followed for 3 years, 10 patients followed for 2 years, plus 10 patients followed for 1 year, and so on.) There were 1441 patients in the DCCT study followed from 3 to 9 years.
In this study, retinopathy first appeared at a rate of 4.7 patients per 100 patients years in the "intensive" or strict control treatment group vs 1.2 patients per 100 patient years in the "conventional" or loose control group. This represented a 76% risk reduction. In patients who had early retinopathy at the start of the study, it progressed at a rate of 7.8 patients per 100 patient years in the "intensive" or strict control group vs 3.7 patients per 100 patient years in the "conventional" or loose control group. This represented a 54% risk reduction.
The appearance of abnormal albumen excretion > 300 mg/24 hr (early kidney disease, but not kidney failure) was 0.3 vs. 0.2 patients per 100 patient years (intensive vs conventional) in those patients who had no eye disease and 1.4 vs 0.6 patients per 100 patient years in those patients who had early eye disease at the beginning of the study. This represented a 44% and 56% reduction of kidney disease.
The question whether or not prepubertal children are protected from the risk of high blood sugar until they enter puberty is still being argued. There probably is some protection prior to puberty as it is extremely rare to develop complications until at least 5 years after the onset of puberty.
It is really very difficult in my opinion to quantitate the long term risk of severe complications such as blindness and kidney failure as these complications do not usually occur until at least 10 years after the onset of puberty (the DCCT study wasn't carried out long enough to assess the risk with intensive control). I think it is important to remember that most statistics describing the risk of long term complications were derived before the long term use of home blood glucose monitoring. If detected early, both eye disease and kidney disease can often be successfully treated to prevent or delay the more severe problems.
Finally, it is unlikely that pregnancy caused the kidney problems in your friend. If kidney problems are present before the onset of pregnancy they may become worse during pregnancy. It does not seem however that pregnancy itself increases the risk of later kidney disease.
Original posting 18 Oct 97
Last Updated: Tuesday April 06, 2010 15:08:54
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