Hypoglycaemia is the term used to describe what happens when our blood sugar drops. It can cause weakness, hunger, sweating, heart palpitations, tremors or shakiness, fainting, dizziness, nausea, headache, and disturbed vision. It may become so severe that it causes mental symptoms like confusion.

While hypoglycaemia most often affects diabetics after a large dose of insulin, non-diabetics may also sometimes experience these symptoms, especially when the body secretes a large amount of insulin. So, if you’ve ever felt shaky, sweaty and weak after a meal in the absence of diabetes, it may be reactive hypoglycaemia – when blood sugar drops as a result of too much insulin.  

When you are at work, this might be particularly unpleasant, especially when you need to focus on an important task.

However unpleasant, in most cases hypoglycaemia after a meal isn’t life-threatening. It is the result of your body producing too much insulin after consuming a heavy, carb-laden meal. The extra insulin removes too much glucose from your bloodstream, resulting in the symptoms mentioned above. 

Other, more serious causes of reactive hypoglycaemia include pancreatic tumours, alcohol, surgeries such as gastric bypass or ulcer treatment, or insulin resistance (a metabolic disease which often includes conditions like obesity and high blood pressure).

What can you do to prevent these 'sugar crashes' after meals?

The best solution to combat hypoglycaemia is to ensure that the pancreas makes just enough insulin and that the blood sugar level never drops too much or too rapidly.

This can be avoided by eating foods that do not overstimulate the release of insulin. These include unrefined carbohydrates such as white pasta, white bread, rolls, biscuits, sweets, white rice and fruits with a very high sugar content such as grapes.

Alcohol and sugary sodas can also cause insulin to spike.

If you are prone to hypoglycaemia and you don’t have any underlying conditions, or if you are pre-diabetic, Dr Ingrid van Heerden, a registered dietitian, recommends the following:

- Never skip breakfast. A diet such as intermittent fasting might not be ideal for you if you are prone to low blood sugar levels.

- Don’t skip meals and never let your blood sugar drop too low.

- Eat small, frequent, balanced meals based on the following principles: it has to include a whole grain, a healthy source of fat, lean protein and fibre.

- Have a healthy snack at work to avoid this happening, especially late in the afternoon when driving home. Wholewheat crackers, dried fruit, almonds or apple slices with peanut butter are ideal.

- Limit your alcohol levels, as excess alcohol may also cause your blood sugar levels to spike and then drop.

- Get enough sleep. When you lack sleep, your cortisol levels (a stress hormone) rise, which can also end up causing your blood sugar levels to crash. 

https://www.health24.com/Diet-and-nutrition/News/why-does-my-blood-sugar-drop-after-eating-20200727