Diabetic ketoacidosis is associated with an excess secretion of counterregulatory hormones. The effect of rehydration on these endocrine derangements before insulin administration is unknown. Therefore, we measured the effect of rehydration with hypoosmolal fluid (220 mosmol/kg) on blood glucose (BG), immunoreactive insulin (IRI), immunoreactive C-peptide (IRCP), immunoreactive glucagon (IRG), human pancreatic polypeptide (hPP), growth hormone (GH), prolactin (PRL), cortisol, aldosterone, renin (PRC), epinephrine, norepinepnrine, and parathyroid hormone (PTH) in ketoacidotic diabetic patients [pH 7.03 ± 0.05 (SEM); n = 8] and in patients (n = 2) with nonketotic hyperglycemia (BG, 29.8 mmol/L and 46.8 mmol/L). The cumulative net fluid balance after rehydration was 4364 ± 690 ml. Basal insulin was inappropriately low, and IRCP was below the normal range (1.5 ± 0.5 ng/ml). Serum osmolality fell during hypoosmolal rehydration (n = 9) from 335 ± 11 to 315 ± 9 mosmol/kg. Rehydration with hypoosmolal fluid with bicarbonate added at a pH of less than 7.2 induced a fall in BG ranging from 6.1 mmol/L to 22.6 mmol/L, or of 16.7% to 79.8% of the initial BG level, as well as a decrease in plasma lactate and urinary glucose. These effects were paralleled by a decrease in IRG, cortisol, epinephrine, norepinephrine, aldosterone, and PRC. No fall in BG was seen in one patient whose dehydrated state was maintained by infusion of isotonic saline. Low dose insulin treatment was initiated in all patients immediately when no further fall in blood glucose levels was achieved.

We conclude that rehydration improves the metabolic situation in severe diabetic hyperglycemia and ketoacidosis by reducing (a) the availability of counterregulatory hormones and (b) peripheral insulin resistance on a cellular level. Thus, proper rehydration will support the beneficial action of simultaneous low dose insulin treatment in patients with severe hyperglycemia.

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