Many users of home blood glucose monitors may be quick to panic in response to a sudden blood sugar spike. But did you know that there are many factors, apart from the food you eat, that may temporarily influence your blood glucose level? Many of these factors affect the hormones involved in regulation of glucose and insulin.

Stress – Cortisol, a stress hormone, has been found to decrease insulin sensitivity and to increase blood glucose levels in some literature studies. A study published in 2016 examined a Japanese population that showed a significant association between higher serum cortisol levels and decreased insulin secretion. Another study from 2020 suggested that cortisol was responsible for contributing to hyperglycemia in diabetic patients by affecting insulin secretion and by promoting glucose production.

Sleep deprivation – Lack of sleep may contribute to an increase in blood glucose level, as well. Glucose metabolism and insulin sensitivity was impaired following sleep deprivation. Shorter sleep duration is also thought to increase appetite by affecting appetite-regulating hormones, namely, ghrelin and leptin. Increased appetite may also indirectly increase blood glucose if followed by increased food intake. A study showed that even healthy subjects, after undergoing a week of under 4 hours of sleep showed a slower rate of glucose clearance and lower acute insulin response to glucose in the next morning, compared to when they were subsequently put in bedrest for 12 hours.

Dehydration – A 2017 study showed that 3 continuous days of low water intake, resulting in dehydration, was linked to higher cortisol levels and higher serum glucose levels during oral glucose tolerance test in subjects with type 2 diabetes. An earlier study from 2011 showed that even healthy individuals were more likely to experience new-onset hyperglycemia in response to low water intake. This finding stated that lower water intake was likely to change the level of vasopressin, a hormone that is thought to play a role in glucose production in the liver.

Illness/Infection – In a similar way to psychological stress, physical stress, such as an infection or pain (e.g. sunburn), may cause changes in your hormone levels. Like cortisol, adrenaline is another stress hormone. Adrenaline can increase blood glucose by liberating glucose from glycogen, a huge store of glucose molecules that are linked to one another. It can also promote fat tissues to break down and release glycerol molecules. These molecules can reach the liver via the bloodstream to become ingredients for glucose production.

Dawn phenomenon – The “dawn phenomenon” refers to the episode of blood glucose spike in the early morning for patients with diabetes. Growth hormones are thought to play a role through its insulin-antagonistic effects.

Physical activity – Exercise has several mechanisms of action that explain the lowering of blood glucose. Among many functions, it can 1) increase insulin sensitivity, 2) increase function of beta-cells in the pancreas, 3) use glucose as energy, and 4) lower visceral body fat.

Menstrual cycle – A study from 2013 encouraged women with diabetes to take into consideration that frequency of hyperglycemia seemed to be higher during the luteal phase, compared to the follicular phase of the menstrual cycle. Another study from the same year suggested that an increase of blood glucose and insulin resistance during the luteal phase was due to increased level of progesterone that lowered insulin sensitivity. However, the mechanism is not very clear, yet.

Medications – Some of the medications known to be associated with blood sugar spike include steroids, antipsychotics, hormonal contraceptives, statins, niacin (vitamin B3), and certain decongestants, such as pseudoephedrine.

Note that although these elements may also affect the blood glucose levels of the healthy, those with diabetes are believed to be more easily affected. Keeping track of the overall pattern of your blood glucose readings may give you a better idea for your course of action in response.