All those people who have been living with type 2 diabetes for many years or have recently been diagnosed with this medical condition, must be aware of how blood sugar levels can fickle, and why it’s important to control fluctuating blood sugar levels. According to the National Institute of Health, by properly controlling the blood sugar levels, a diabetic person is at a lower risk of potential diabetic complications such as kidney damage, stroke, nerve damage, vision issues, and heart disease. 
It’s normal for anyone to experience small variations in their blood sugar levels at different times of the day and depending upon their diet, activities, and many other factors. Blood sugar fluctuations are hardly seen in non-diabetic people as the body regulates the sugar levels in the blood by insulin secretion and the body’s natural processes. However, if the blood sugar fluctuations are large enough, one can experience symptoms such as dry mouth, fatigue, confusion, blurred vision, and headaches. When the blood sugar levels go critically out of range, its negligence can have severe short and long-term side effects.
An individual would be able to figure out whether their sugar levels are going high or low only when it is tested and repeated throughout the day with or without an empty stomach. This is done by a finger prick test, where the finger is pricked and the released drop of blood is placed on the machine to be analyzed. This is referred to by medical specialists as capillary blood glucose. 
Blood sugars may zoom up all of a sudden and drip low if tried to adjust with insulin, physical activity, or proper diet. Most people feel confident in managing their diabetes, but in reality, even they don’t know what could affect their blood sugars in unexplained ways. To avoid getting ahead with pesky high and low blood sugars because of the corrections, it’s important to understand different unexpected triggers that can send one’s blood sugars on a roller coaster ride.
Here are 10 surprising factors that can make blood sugar levels fluctuate. Look out for them. [1,3]
Being dehydrated means the body is falling short of fluids. Dehydration can lead to hyperglycemia- the spike in blood sugar levels. To make it even worse, the concentrated sugars in the circulation can cause the person to urinate more, eventually resulting in extreme thirst. If it is long-term, it can even cause serious problems with the small blood vessels of the body. Thus, diabetic people should be especially watchful about drinking sufficient water or other calorie-free beverages all day long to keep their body well hydrated and blood sugars in check. [2,4]
2. Insufficient Sleep
It has been noticed that even if a person does not sleep for one night or has very little sleep, the body would start using less insulin which means there will be insulin resistance. This is because, our body releases insulin and regulates blood sugars naturally according to our circadian rhythms- the natural pattern of sleep and wakefulness. The correlation between sleep and elevated blood sugars goes both ways. Not only diabetics but even healthy people would show blood sugar fluctuations when they are sleep deprived. Late-night snacking on sugary foods to compensate for low energy levels of fatigue can be its reason. [1,2]
3. Too Much Caffeine
Some people are addicted to daily cups of coffee containing caffeine. Those who have blood sugars extra-sensitive to caffeine are likely to encounter high blood sugars after intake of coffee even without a sweetener. 
4. Artificial Sweeteners
As per a few research studies, it has been found that artificial sweeteners can increase blood sugar levels. However, still more research studies and evidence are needed to confirm this. A recent review article suggested that artificial sweeteners may contribute to compromised glucose homeostasis, so they may not be completely neutral in sugars. [3,4]
5. Some Medications
As medications can have side effects, some prescription and over-the-counter drugs can derange blood sugar levels. One best example of medications known to spike blood glucose levels includes steroids like prednisolone. Others that may cause the shooting up of blood sugars are certain antidepressants and antipsychotics, nasal decongestants, diuretics, and birth control pills. However, there are even the drugs like those given to diabetics that can reduce the blood sugar level lower than normal readings. [2,4]
6. Nasal Sprays
Some nose sprays have been tested and found to contain chemicals that trigger the liver to make more blood sugars. 
7. The Infamous ‘Dawn Phenomenon’
It is common for both diabetics and non-diabetics to have elevated blood sugar levels as soon as they wake up early in the morning because of the surges in their hormones. This usually is experienced when the body prepares to wake up by the release of certain hormones including cortisol, between 2 and 8 a.m. These hormones cause insulin resistance which makes the blood sugars rise. Alternatively, those who are taking too much insulin or diabetes medications at night or not eating proper dinner may start their day with low blood glucose levels. 
8. Skipping Breakfast
No one should skip the first-morning meal, as after starving for long hours the whole night and morning, certainly, the blood sugars can increase after having lunch and dinner. 
9. Gum Disease
It can be a blood sugar spiker as well as a complication of diabetes. 
10. Other Potential Causes
Time of the day- At a later time of the day, it could be difficult to control blood sugar levels.
Extreme weather- If it is bitterly cold or swelteringly hot, in either case, it would be hard to keep diabetes in control. Extreme heat like in hot baths, hot tubs, or sunburns can dilate the blood vessels which makes insulin absorption quicker and could result in low blood sugar levels.
Traveling- During traveling, diabetic people should be extra cautious. This is because there is a change in time zones which in turn disrupts medication schedule and sleeping habits, and causes unusual eating. There are chances of people smoking or having alcohol, and even becoming dehydrated. All of these could affect blood sugar levels. [1,4]
- https://www.cdc.gov/diabetes/library/spotlights/ blood-sugar.html