**EP27: Blood Sugar And Testing**
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Hi, my name's Dr. Warwick Bishop, and I'd like to welcome you to my consulting room. Today, I'd like to tell you a little bit about a patient I saw this week. In particular, I'd like to talk a bit about glucose and blood sugar levels and how they're assessed.
The patient I saw was in her mid to late 60s. She was carrying a little bit of weight around the middle. Her triglycerides were elevated a little bit, and her good cholesterol, her HDL, was down a little bit. Her most recent blood test had shown a blood sugar level of 6.1. When I spoke with her, it became clear that her GP had organized these blood tests and had wanted to follow through. The GP had organized a glucose tolerance test.
Interestingly, the patient had said she'd had one of these before. She said she remembered that her blood sugar level before the test, before drinking the glucose, was a bit high, but after drinking the glucose, it was normal. That's interesting. I wonder what that says to you. What that says to me is that this lady, quite possibly, is producing insulin, but not enough at rest. When her insulin is triggered by a carbohydrate or a sugar load, her insulin response is very brisk. Her insulin levels go high and drive the blood sugar levels down to normal range and perhaps even lower.
This means that her glucose tolerance test, which shows a blood sugar level at the time of fasting before drinking the sugary drink and then two hours after drinking the sugary drink, doesn't tell us exactly what happens with the sugar levels in between. What I suspect happens for this lady is that her sugar level runs up, her insulin level runs up, her insulin drives the sugar back down, and so by the time the second blood test at two hours is taken, her sugar levels are back to normal.
Well, because her sugar level's back to a normal range, the test is reported as normal. However, we know her fasting glucose is elevated, her triglycerides are elevated, her good cholesterol, her HDL, is down, and she's carrying weight around the middle. So it seems odd that the test that should be looking for an abnormality in this space is completely normal when she seems to have some of the signs.
What I said to this lady is, "Look, hold off on the glucose tolerance test because of the limitations I've just described." What I think we really want to know is whether she's resistant to the insulin she produces or whether she produces a lot of insulin at any given time. The test I tend to use for this to try and evaluate what's going on and try and understand the insulin resistance that a patient may have is HOMA, H-O-M-A. That stands for homeostatic metabolic assessment. You don't need to remember that, but very simply, the way we do it is on a fasting blood, we check the blood sugar level. On the same fasting blood, we check the insulin level.
There's a simple calculation that we multiply, and we get an index. That index gives us an idea as to the likelihood of this patient having insulin resistance. If the sugar is a bit elevated and the insulin is considerably elevated, then the index is high. This clearly shows that the person is using a lot of insulin to keep their sugar under control. This means that they're insulin resistant. If the sugar's in the normal range and the insulin's in a normal range or lowish, then these people are not insulin resistant.
Well, why is this important? The reason why I think this is important is for this particular lady. Her fasting glucose was not high enough to demonstrate diabetes, and it was unlikely that the glucose tolerance test was going to demonstrate diabetes. But the thing that was probably going to drive her cardiovascular risk into the future is whether she's insulin resistant.
Because insulin resistance is closely linked to elevated triglycerides, lower HDL levels, and central adiposity, these particular patients, in my experience, really do benefit from being aware of the carbohydrate they consume. If they can start to cut it down and expose their body less and less to carbohydrate, they tend to turn down their insulin response, lose weight, lower their triglycerides, and improve their HDL cholesterol. Overall, they have a much better picture profile for their cardiovascular risk into the future.
So when it comes to glucose, blood sugar levels, and testing, a glucose tolerance test may not always be the best solution, and perhaps looking at insulin resistance with a HOMA using simultaneous blood sugar and insulin could be the answer.
I hope you found that interesting and informative. As always, I wish you the very best, and I'd like to thank you for joining me. Goodbye.
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