July 6, 2007

Why Type 2s have 3 Times More Neuropathy than Type 1s

A very interesting study presented at the recent ADA Scientific Sessions, which did not get picked up by the media, found that Type 2s have three times as much neuropathy as Type 1s.


From the Diabetes in Control report:
"Factors associated with higher diabetic neuropathy in a multivariate analysis were male gender (P=0.02), increasing age (P<0.0001), type 2 diabetes (P=0.02), increasing duration of the disease (P=0.0006), and HDL cholesterol at or below 40 mg/dL for men or 50 mg/dL for women (P<0.0001)."

The researchers concluded that "neuropathy and painful neuropathy are mainly associated with type 2 diabetes, potentially via the metabolic syndrome, which encompassed the majority of the strong predictors found."

When I read this, it occurred to me that there may be another, much better, explanation for why Type 2s have so much more neuropathy than Type 1s, and one that has nothing to do with "metabolic syndrome".

The explanation may lie in the fact that doctors consider it normal for Type 2s maintain blood sugars that are well over 140 mg/dl (7.7 mmol/L) all the time. In contrast, Type 1s tend to seesaw between highs and lows, and so while they may go quite high they rarely stay high for more than a short time, because they use corrective boluses to get their blood sugars back down.

Doctors give Type 1s the tools needed to reduce exposure to very high blood sugars: intensive insulin regimens and pumps. A Type 1 who is high will use a corrective bolus to bring down the very high blood sugar as soon as it is noticed.

In contrast, Type 2s mostly are given oral drugs which are incapable of reducing their very high blood sugars to levels anywhere near those that would prevent neuropathy. So they spend the entire day at levels a Type 1 would immediately correct.

Even when they put Type 2s on insulin, doctors rarely instruct Type 2s in how to use bolus insulin to correct highs. Most Type 2s, in fact, are only given basal insulin, which leaves them very high hours each day after eating the low fat/high carb meals they are still instructed to eat.

Most Type 1s are also instructed to keep their fasting blood sugar well under 140 mg/dl, where many, if not most Type 2s have doctors who do nothing when their fasting blood sugars is 160 mg/dl (8.9 mmol/L) or even higher.

We know, based on the research I've explored on my Research connecting organ damage with blood sugar page, that the incidence of neuropathy rises very swiftly as soon as people's 2 hour GTT test result goes over 140 mg/dl. This finding has been duplicated in several studies. This suggests that several hours of exposure to a blood sugar over 140 mg/dl promotes the development of neuropathy.

So it is very clear to me that the real explanation for why Type 2s have so much neuropathy is not likely to be anything intrinsic to their disorder. It is, instead, the result of the extremely poor blood sugar control that their doctors consider normal.

One reason that doctors allow Type 2s to maintain such damaging blood sugars is that they relay so heavily on A1c, which reflects a mean glucose, rather than looking at peaks. In addition, thanks to the ADA's recommendation, they still consider the 7% A1c "safe."

The research shows that for Type 1s a 7% A1c will significantly reduce complications. But UKPDS showed that the reduction for Type 2s at the same A1c is much less.

That is because of how that A1c is achieved.

Type 1 with a 7% A1c may have a fasting bg of 110 mg/dl and spend many hours at a near normal blood sugar, punctuated by hour long excursions to 300 mg/dl now and then that raise the A1c from the normal range.

In contrast, the Type 2 controlled on oral meds alone, as most are, or on an inadequate does of Lantus, may have that same 7% A1c but will be more likely to have achieved it by having blood sugars that are much closer to the mean--172 mg/dl (9.6 mmol/L) all day long. That is why Type 2s have many more complications than Type 1s at the same A1c. For a Type 2, the "safe" A1c--no matter what the number--is one that is achieved by being under 140 mg/dl as much of the day as is possible.

If you are a Type 2 and want to avoid neuropathy--the condition that leads to amputation--do what you can to keep your blood sugars under 140 mg/dl (7.7 mmol/L) If you spend many hours a day with blood sugars over that level you will develop neuropathy.

The tools that will let you keep your blood sugar at that level are these:

1. Avoid eating carbs. There is nothing "healthy" about a food, no matter how good for someone without diabetes that raises blood sugar, and carbs--including whole grains and pasta--do raise blood sugar, often very high.

2. If your current drug regimen is leaving you over 140 mg/dl (7.7 mmol/L) for hours at a time, and you have tried all the currently available oral drugs, ask your doctor to prescribe insulin for you and, if possible, ask to see a Certified Diabetes Educator who can teach you how to use insulin properly. If you are still going high on Lantus, Levemir, or NPH, ask to be taught how to use meal time insulin too.


Anonymous said...

It may also be that a larger number of type 2 diabetics make little to no effort to take control of diabetes, and it takes a long time for that to catch up to them

whereas with type 1's, we must immediately take some sort of control or we will die quickly

Jenny said...

That's probably true, but as I explained in a later posting about how Type 1s see Type 2s, one major reason that Type 2s neglect their control is that their doctors encourage them in the belief that an 8% A1c is fairly decent control and do not offer them insulin even when their blood sugar is not controllable with oral drugs.

Many are not given meters or taught to test after meals, and may even be told that fat, not carbs, raise blood sugar. These aren't guesses on my part. I've run into people like this--including some with graduate degrees.

Their own "fault" is that they trust too much in their family doctor who hasn't taken training in diabetes treatment since 1982.

Unknown said...

Is it really true that doctors advise Type 2s that 8.0% A1C and a fasting of 140 is acceptable control? I was diagnosed with Type 2 two months ago (A1C 11.8, FBG 290), and my doctor's targets are much more aggressive even than the Diabetes Education Center staff. He wants my FBG in the 80-100 range, with a post-prandial of less than 160. The A1C goal he's suggested is between 6.0 and 6.5.

It was neuropathy pain that got me to the Doctor in the first place. I'm scared to death of not getting it reversed. It's still early, but I've got by FBG down to the 95 range, and my post-prandial in the 150 range. The complications of this disease are so freaking scary that I don't understand how anyone could not totally throw themselves into fighting it.