Missing Meals? Avoid Dangerous Blood Sugar if You Have Diabetes

It's important to know your numbers before adjusting meds

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Skipping a meal is typically no big deal. But if you have diabetes, missing meals can throw off the important balancing act between food intake and medication.

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The result is blood sugars that are too low (hypoglycemia) or too high (hyperglycemia) — and that’s dangerous.

“If you take medications for diabetes that can cause low blood sugars, you should try not to skip meals,” says registered dietician Dawn Noe. “If you’re just not up to eating on a regular schedule, talk to your doctor about diabetes medications that won’t cause low blood sugars,” she says. 

Monitoring sugars is vital

When you’re ill or just don’t feel like eating much, it’s important to monitor your blood sugar levels more closely than ever. How often depends on whether you have type 1 or type 2 diabetes and what medications you take.

For type 1 diabetes: Be sure to monitor your blood sugar before meals and before bedtime, typically four times per day, says diabetes specialist Bartolome Burguera, MD.

Beyond that, check your blood sugars if you notice symptoms of low blood sugar. Those symptoms include:

  • Hunger
  • Shakiness or nervousness
  • Sweating
  • Dizziness or light-headedness
  • Sleepiness
  • Confusion
  • Difficulty speaking
  • Anxiety
  • Weakness

For type 2 diabetes: If you are taking a sulfonylurea medication, check your blood sugars at least twice a day — in the morning and at bedtime.

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“It’s important to keep in mind that sulfonylureas may cause blood sugar to drop during the day if you don’t eat anything after taking your medication,” Dr. Burguera says.

If your only treatment is metformin, you may not need to check your blood sugar more than once a day. This medication doesn’t typically cause hypoglycemia.

It is important to be aware of the symptoms associated with low blood sugars and be ready to check your blood sugar and to eat or drink something to correct a low blood sugar if needed, Dr. Burguera says.

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Also watch for high blood sugar

If you’re not eating due to an acute illness (e.g., the flu or an infection), it’s also common for your blood sugars to rise.

“When you have diabetes and are acutely ill, you should check your blood sugars up to four times per day, drink plenty of fluids and contact your doctor if your blood sugars are consistently over 250,” Ms. Noe says.

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Controlling diabetes when you’re not hungry

If you find that you’re eating less due to an illness or other factors, your medications may need adjusting, so it’s important to talk to your doctor. Meanwhile, here are some general guidelines:

  • Mealtime insulin — For mealtime insulin, if you skip the meal, you should also forego the mealtime insulin.
  • Long-acting insulin — The dosage for long-acting insulin is not usually based on food intake, so your doctor will not likely recommend a dose reduction.
  • Other medications — There are some diabetes medications that will lower your blood sugar when high, but won’t normally cause hypoglycemia. They may or may not need adjustment, depending on how much you’re eating. These medications include metformin, SGLT-2 inhibitors and DPP4 inhibitors.

Watching for symptoms isn’t enough

Although you may think you’ll know from experience when your blood sugar is out of whack, regular monitoring is the only way to make sure.

“It’s important to keep in mind that the symptoms of high or low blood sugars may fade away after several years of living with diabetes, especially if your blood sugars have not been well controlled,” says Ms. Noe.

“Also, some of the symptoms of high blood sugars and low blood sugars are the same, so it’s important to check your blood sugar first, if possible, before treating it,” she says.

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