May 18, 2007

UKPDS found Many More Complications in Type 2 than Type 1 at 7% A1c

A visitor commented on the previous post with the remark that a Type 1 might have great difficulty achieving the 7% A1c safely. That could lead into a whole nother debate about what is a safe blood sugar target for people with Type 1, but that is a debate that would be more appropriately conducted between people with Type 1, which I am not. So I'll leave it alone.

But that comment made me want to focus on another very important point about the UKPDS study. The UKPDS study was an attempt to duplicate the DCCT study which first came up with the finding that lowering the A1c to 7% resulted in a significant drop in microvascular complications.

The important thing to realize--which your doctor may not know--is this: The DCCT study only involved people with Type 1 diabetes. The UKPDS study was an attempt to do the same thing with a population of recently diagnosed people with Type 2 diabetes. It found was that people with Type 2 had a much higher incidence of microvascular complications at the 7% A1c level than had the Type 1s involved in DCCT.

Though there was an improvement in the incidence of serious complications between those with 7% A1cs and those with 9% A1cs in the UKPDS, the improvement was much less pronounced in the Type 2s than it had been for DCCT's Type 1s. Far more Type 2s with 7% A1cs had serious retinopathy, kidney damage, nerve damage, etc than did the Type 1s with that A1c.

The reason for this is most likely that people with Type 2 usually have elevated blood sugars for at least a decade before they are diagnosed. During that decade, uncontrolled high blood sugars wreak a lot of damage on nerves, capillaries, and the retina. In contrast, people with Type 1 get diagnosed very swiftly because they go into a health crisis, so they don't have that decade of insidious damage to contend with when they get back into control.

In addition, because people with Type 2 diabetes often have very high levels of circulating insulin, due to insulin resistance, they may be more prone to experiencing damaging tissue changes, thanks to that high insulin level and the production of other hormones associated with insulin.

If doctors would look at people's blood sugar after a meal, instead of screening for diabetes using only the fasting plasma glucose test, people with Type 2 diabetes (and quite a few of us with milder forms of MODY) would get diagnosed before the high blood sugars after every meal had a chance to destroy our organs. Sadly, they don't.

I am still getting mail from people whose doctors tell them to ignore blood sugars over 200 mg/dl after every meal because their fasting blood sugar is under 125 mg/dl and hence they are, in the doctor's mind, not diabetic. So it's pretty clear to me why almost 1/2 of all "newly diagnosed" type 2s already have at least one significant, diagnosable diabetic complication--usually early kidney damage or neuropathy.

But because Type 2s already have microvascular complications, they need to lower their blood sugar much more dramatically to prevent those complications from getting worse. There is much anecdotal evidence that achieving 5% A1cs can repair neuropathy and early kidney changes, but the blood sugars associated with the 7% A1c are not going to do that.


Anonymous said...

Excellent comments