Prediabetes diagnosis as an older adult: What does it really mean?

As our bodies age, the risk of type 2 diabetes increases. It is estimated that 25% of adults older than 65 have type 2 diabetes, while half of people over 65 have prediabetes. We know that having type 2 diabetes as an older adult requires proper lifestyle, and sometimes medications, to control the disease and reduce the risk of diabetes-related complications, but the implications of having prediabetes at this age are not totally clear.

What is prediabetes?

Prediabetes is a phase that often precedes the development of type 2 diabetes. Both diabetes and prediabetes are diagnosed based on laboratory test results. The most traditional test is known as fasting plasma glucose (sugar) (FPG). It is usually measured in the morning after fasting for eight to 10 hours. A value less than 100 mg/dL is considered normal. An intermediate result (impaired fasting glucose) is 100 to 125 mg/dL, and this would indicate prediabetes; a value equal or higher than 126 mg/dL is suggestive of diabetes. Diabetes and prediabetes can also be diagnosed by an oral glucose tolerance test (OGTT). Plasma glucose is measured before and two hours after orally ingesting a drink containing 75 grams of sugar. A value less than 140 mg/dL is considered normal, 140 to 199 mg/dL is considered intermediate (impaired glucose tolerance/prediabetes), and a value equal to or higher than 200 mg/dL is suggestive of diabetes. A third test to diagnose diabetes and prediabetes is the measurement of glycohemoglobin (A1c) in the blood. A value less than 5.7% is considered normal, a value between 5.7 and 6.4% is considered intermediate (prediabetes), and a value equal to or higher than 6.5% is suggestive of diabetes. A repeat test is usually required to confirm a prediabetes or diabetes diagnosis for all of these laboratory tests.

What is it important to know if you have prediabetes?

In young and middle-age adults it is extremely important to know if someone has prediabetes, as it not only implies a higher risk of developing type 2 diabetes, but it also frequently occurs with conditions such as obesity, high blood pressure, and elevated fats in the blood (like cholesterol and triglycerides), all of which increase the risk for cardiovascular disease. The good news is that type 2 diabetes can be prevented, or at least delayed. The Diabetes Prevention Program (DPP) showed that in a large group with prediabetes, improving diet and engaging in regular physical activity (that results in a 7% weight loss) led to a 58% reduction in the progression to type 2 diabetes. Therefore, lifestyle modifications are usually recommended to all adults who are diagnosed with prediabetes. In younger and middle-age adults, the use of some medications, in particular metformin, may also be appropriate.

Are the implications of being diagnosed with prediabetes as an older adult the same as for a younger or middle-age adult?

Recent research has provided some interesting information about this issue. The Atherosclerosis Risk in Communities (ARIC) Study followed 4,000 adults who were 45 to 64 years old in the late 1980s. A recent analysis of 3,412 individuals from that group who were 71 or older found that those who had prediabetes (based on FPG or A1c levels) at the start of this analysis were more likely to remain in this intermediate state of prediabetes, or return to normal glucose values instead of progressing to diabetes, after a follow-up period of 6.5 years. In fact, fewer than 12% of people in this study progressed from prediabetes to diabetes, no matter what test was used to measure blood sugar levels.

These findings would suggest that having prediabetes as an older adult does not seem to be as important in identifying the risk of progressing to type 2 diabetes as it is in younger adults.

Important considerations of the new research

It's important to note that the ARIC study didn't use all the tests for diabetes and prediabetes previously explained; they only used FPG and A1c levels. Therefore, some people could have been identified as having progressed to diabetes if other tests had been included in the analysis. Second, it is known that a third of the whole ARIC study group followed since the late '80s developed diabetes before they reached 71 years of age, and therefore were not included in this analysis. The individuals who didn't develop diabetes before age 71 may actually have a lower risk of developing the disease than those who developed it as middle-age adults in this study population. Finally, the study group comprised primarily white adults, so the results may not be entirely applicable to other populations with a much higher risk for type 2 diabetes. (In fact, the risk of progressing to type 2 diabetes was higher in the black subgroup in the study when compared to their white counterparts). The authors notably made some important adjustments to the analysis in the study to control for all these factors, but it is difficult to totally eliminate their potential role in the study findings.

You can't go wrong with eating healthy and being active, no matter what age you're diagnosed with prediabetes

Whereas it is very likely that having prediabetes as an older adult does not have the same implications as it does in younger adults, following general lifestyle recommendations to eat healthy and engage in regular physical activity seems prudent when possible. In fact, healthy lifestyle changes were very successful in reducing the risk of type 2 diabetes in people 65 and older in the DPP. Having a healthy lifestyle as an older adult provides many additional health benefits to the body and mind.

It is important to acknowledge that not all older adults are able to follow these recommendations, due to the presence of multiple acute and chronic medical issues that affect their eating habits and limit their physical activity, and managing these conditions may be more important than a slight elevation in their blood sugar levels. In the end, it is important to discuss the implications of being diagnosed with prediabetes with your health care providers, and to individualize your treatment.