ArcaMax

DEAR DR. ROACH: My question is: What is the difference between prediabetes and diabetes, and which do I have? I am male, 85 years old, 170 pounds, and 6 feet and 1 inch tall. I was treated for heart disease with Coreg, Crestor, isosorbide, lisinopril and amlodipine.

About one year ago, the cardiologist added 5 mg of Farxiga for its heart and kidney benefits. About 12 years ago, I was diagnosed with prediabetes and promptly changed my diet to greatly reduce my intake of sugar and carbs; I lost about 25 pounds. This week, my blood test showed an A1C level of 5.9%, well below the 6.5% that is indicated for diabetes.

Can you estimate how much Farxiga has reduced my A1C and what it might be had I not been taking Farxiga? Without Farxiga, could I have been diagnosed with diabetes? -- P.R.

ANSWER: Both prediabetes and diabetes are metabolic abnormalities in which the body cannot use sugar properly. There are several different types of diabetes. In North America, Type 2 diabetes is the most common type, in which there is resistance to the action of insulin. The molecular details of insulin resistance aren't completely understood.

People with diabetes are at a higher risk for many conditions, including heart disease and stroke. There is a much smaller increase in risk for prediabetics compared to diabetics, but there is still an increase in general when compared to a person with normal blood sugar.

Dapagliflozin (Farxiga) is part of a class called sodium-glucose cotransporter-2 (SGLT2) inhibitors, which work by preventing the kidneys from reabsorbing sugar in the proximal tubules of the nephrons, the functional unit of the kidney. The sugar goes into the urine, making less work for the pancreas. This has been shown to prevent people who are prediabetic from getting diabetes by about a third. The expected side effect of urine infections is much less than one might expect -- only 1% or 2% in most studies.

In people with diabetes, Farxiga drops A1C levels by roughly 0.6%, which is not a huge amount compared to other diabetes medicines. But in your case, this would be the difference between having prediabetes at 5.9% (where you are now) and having diabetes with an A1C level of 6.5%.

Of course, we won't ever know for sure whether you would have gone on to have diabetes, but I think it is possible. The changes in your diet and weight loss were also likely to have had a benefit, and those might have been as important or more so than the medication over the past 12 years.

Both SGLT2 inhibitors and GLP-1 inhibitors (such as semaglutide) have shown benefit in reducing heart disease risk with certain populations. Reducing new-onset diabetes is an additional benefit when used for this indication.

DEAR DR. ROACH: I bought a natural, plant-based supplement online to treat my prediabetes. My A1C level went from 6.7% to 5.9% in two months. I'm a 70-year-old woman. -- N.D.

ANSWER: Your A1C was in the diabetes range when it was 6.7%, and even though it is now in the range of prediabetes, once you have diagnosed diabetes, this remains your diagnosis even if your blood sugar becomes normal.

I don't want to argue with apparent success, but the plant-based supplement you sent me contains several ingredients, none of which have been proven to significantly lower blood sugar. The company making it provided no studies to show effectiveness in combination. Of course, it still might have worked for you.

I wonder if you changed your diet or exercise, which might be responsible for the improvement in your blood sugar.

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Dr. Roach regrets that he is unable to answer individual letters, but will incorporate them in the column whenever possible. Readers may email questions to ToYourGoodHealth@med.cornell.edu or send mail to 628 Virginia Dr., Orlando, FL 32803.

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