How does reactive hypoglycemia differ from other kinds hypoglycemia?

Hypoglycemia describes the general state of having lower levels of blood glucose than normal. It’s further subdivided into different subtypes of hypoglycemia depending on the presentation, etiology, or both, of the low-blood-sugar response. RH is one such type, in which meal composition, timing, and (likely) insulin response are precipitating factors for hypoglycemic episodes.^[1][2] The term RH is sometimes used interchangeably (and possibly incorrectly) with other subtypes of hypoglycemia, such as hyperinsulinemic hypoglycemia, dumping syndrome, and postprandial hypoglycemia.^{[3][4][5][6][7][8][9]}

Hyperinsulinemic hypoglycemia, while similar to RH in that an imbalanced insulin response is involved, really only refers to any instance of hypoglycemia wherein excessive insulin secretion results in low blood glucose.^[8] Postprandial hypoglycemia, on the other hand, is defined by the timing of meals resulting in low blood sugar.^[3][6] Dumping syndrome may be the most appropriate term to use interchangeably with RH, because it is tied to meal composition, timing, and insulin response. However, definitions of dumping syndrome cite slightly different timing (30–180 mins post-meal) than RH, and dumping syndrome is more often associated with gastric bypass surgery.^[4][5][7]

It’s important to note that these terms aren’t always used consistently in the literature on hypoglycemia. As evidence on RH continues to emerge, clearer alignment with specific definitions will likely follow.