Variable Blood Sugars Associated with Increased Heart Failure Risk

A number of research papers published in the last few years have highlighted a link between drastic blood sugar fluctuations and increased cardiovascular disease risk in people with type 1 diabetes. 

Now researchers have found evidence of a similar phenomenon in type 2 diabetes.

Both Large Increases and Decreases in A1c Raise Heart Failure Risk

The paper, which was published in Diabetes Care this month, followed over 8,500 type 2 participants in the ACCORD trial, none of whom had a history of heart failure.

The researchers analyzed HbA1c variability from baseline to three years. The subjects were followed for an average of an additional 6.5 years following the data collection. The average A1c at the beginning of the trial was 8.3% with an average successive variability of 0.6%. During the follow-up phase, 388 of the subjects were hospitalized or died from heart failure. 

Those who suffered from heart failure during the study were more likely to have experienced drastic fluctuations in their A1c levels during the initial three-year analysis period. 

• Subjects with a 10% or greater increase in A1c showed an elevated heart failure risk of 1.55. 
• More surprisingly, subjects who showed a 10% or greater decrease in A1c also showed an elevated risk of heart failure at a rate of about 1.32.

These results indicate that the stress caused by fluctuations in blood sugar results in more heart damage than reducing one’s A1c prevents.

However, researchers did note that when subjects who experienced hypoglycemic episodes were removed from the data, the effects of drastic drops in A1c were less correlated with an increased risk of heart failure.

This would seem to indicate that, while dramatic increases in A1c do increase heart failure risk, dramatic decreases in A1c only have significant effects on heart health if hypoglycemia occurs.

Why Blood Sugar Fluctuations Affect the Heart

While not specifically discussed in this latest paper, past research gives us insight into why blood sugar fluctuations can be so damaging to the heart muscle, regardless of whether blood sugar is dropping or rising.

When blood glucose levels fluctuate, your body responds in ways that increase oxidative stress on vascular tissue. When these responses happen frequently and on tissues that are already experiencing extra stress due to the effects of elevated blood sugars, such as arterial stiffening, elevated blood pressure, and cardiac tissue damage, the end result can be deadly.

Episodes of hypoglycemia can also play a role in increasing cardiovascular damage, which can, in turn, be exacerbated by blood sugar fluctuations.

• When blood sugar drops below normal, the body responds by increasing heart rate and peripheral systolic blood pressure. 
• This causes the heart to suddenly have to work much harder than normal. 
• This workload increases even more when the vascular system is already damaged by oxidation and stiffening of vessels.

While brief, this extra cardiovascular stress can lead to heart failure under the right circumstances.

How to Keep Your BG Balanced for a Healthier Heart

Reducing your heart disease risk when you live with diabetes has long revolved around reducing blood sugar. But this latest study clearly shows how focusing exclusively on hyperglycemia may not actually be enough to reduce your heart failure risk.

Here are some tips to help you think about your diabetes management with balanced blood sugar in mind:

• Set conservative goals for lowering your A1c
  Aggressive A1c goals may get you to normal blood sugars sooner, but they come at the expense of your heart health. Instead, set goals so you can gradually lower your blood sugar average and move toward a healthy A1c at a pace that won’t stress your cardiovascular system.
• Work with your doctor to add medications gradually
  Adding too many oral medications at once or at too high of doses can cause your glucose average to drop rapidly and may increase your risk of hypoglycemia. Instead, talk to your doctor about a more conservative approach that allows you to integrate and adjust to each dose before increasing it or adding another on top of it.
• Set insulin doses to avoid hypoglycemia
  Insulin is sometimes necessary to achieve any positive change in blood sugars, but using it too aggressively leads to rapid changes and an increased risk for hypoglycemia.
  If your doctor wants you to start on insulin, talk to them about starting with a cautious dose and upping it over time to achieve gradual positive change.
• Focus on time in range rather than your A1c
  Your A1c can be deceiving. It tells you what your average blood sugar has been over the last three months but nothing about how many dramatic fluctuations your body experiences each day. If you use a CGM or are willing to do multiple finger pricks a day, you can easily get a more accurate picture of how stable your blood sugar is. Focus on keeping it within a range determined by you and your doctor rather than shooting for a single number that can be misleading.

While it may seem counterintuitive to value stable blood sugars over normal blood sugars, this most recent study and previous studies into type 1 diabetes heart health, tell us just how important a change in approach is if we want to achieve better heart health outcomes within the diabetes community.