Can Stress Raise Blood Sugar?

The mechanism

When the brain perceives a threat — physical or psychological — it activates two systems. Within seconds, the adrenal glands release adrenaline (epinephrine). Over minutes to hours, they release cortisol. Both are designed to make fuel available for fight or flight, and both act on glucose:

• The liver releases stored glucose (glycogen) into the blood and steps up the production of new glucose from other sources.
• Muscle and fat cells become temporarily less responsive to insulin, so the released glucose stays in the blood for the muscles that will supposedly need it.
• Insulin release is suppressed by adrenaline.

In an emergency that ends in physical exertion, the glucose is burned. In a stressful meeting, a difficult phone call or a sleepless night, it is not — it circulates until the pancreas produces enough extra insulin to clear it.

How big is the effect?

In people without diabetes

Small and short-lived. A healthy pancreas responds to a stress-driven glucose rise with more insulin, and glucose stays within or close to the normal range. Continuous glucose monitor studies of healthy people show rises of perhaps 10–20 mg/dL during acute stress, resolving within an hour or two. It is rarely something you would notice.

In prediabetes and type 2 diabetes

Larger and longer. When insulin resistance already exists and the pancreas is already stretched, the extra demand from stress hormones is not met. People with diabetes commonly see readings rise by 30–100 mg/dL during illness, injury, dental work, surgery, acute pain or intense emotional stress, and glucose can stay elevated for the duration. Severe illness can push glucose high enough to cause ketoacidosis or hyperosmolar state — which is why diabetes care includes a "sick-day plan".

Stress hyperglycemia in hospital

People without any history of diabetes sometimes show high glucose during a heart attack, stroke, serious infection or major surgery. This "stress hyperglycemia" reflects the intensity of the hormonal response. It usually resolves with recovery, but it also identifies people at higher risk of developing diabetes later and is often followed up with an A1C.

Chronic stress

Short bursts of stress hormones are harmless. Sustained elevation is not. Chronic stress — work strain, caregiving, financial worry, poor sleep, depression — keeps cortisol higher for longer, and cortisol in the long run:

• promotes fat storage around the abdomen, the kind most tied to insulin resistance
• reduces insulin sensitivity in muscle and liver
• increases appetite, particularly for energy-dense food
• disrupts sleep, which independently raises next-day glucose

The effect on A1C in any individual is hard to quantify, but population studies consistently find higher rates of type 2 diabetes in people with high chronic stress, depression or short sleep, after allowing for weight and other factors.

Sleep is part of this

Sleep loss is a stressor in physiological terms. Restricting healthy young adults to four or five hours of sleep for a few nights measurably reduces insulin sensitivity and raises glucose; sleep apnea does the same chronically through repeated oxygen drops and arousals. For many people, improving sleep is the most effective "stress management" available for glucose.

What helps

The evidence for specific stress-reduction techniques on glucose is modest, but the direction is consistent:

• Physical activity counters stress hormones directly and uses up the glucose they release. A walk after a stressful event is the closest thing to what the hormones were designed for.
• Sleep: regular timing, seven or more hours, and assessment for sleep apnea if you snore or wake unrefreshed.
• Structured relaxation — mindfulness-based programmes, breathing exercises, yoga — have produced small reductions in A1C in trials of people with type 2 diabetes.
• Treating depression and anxiety, which are common in diabetes and worsen control; treatment improves both.
• A sick-day plan for people with diabetes: check glucose more often when ill, keep taking medication, stay hydrated, and know when to call.

When to see a doctor

If stress-related glucose rises are frequent and large, or your readings stay high after the stressor has passed, your treatment plan may need adjusting. If you do not have diabetes but have noticed high readings during illness, ask for an A1C once you have recovered. Persistent low mood, anxiety or insomnia deserve attention in their own right, and treating them helps glucose too. The high blood sugar guide lists the readings and symptoms that need same-day care.

Frequently asked questions

References