Severe hyponatremia due to rosiglitazone use in an elderly woman with diabetes mellitus: a rare cause of syndrome of inappropriate antidiuretic hormone secretion

Inverse association between glucose-lowering medications and severe hyponatremia: a Swedish population-based case-control study

CONTEXT

Glucose-lowering medications have occasionally been reported to cause hyponatremia, but the evidence is scarce.

OBJECTIVES

To explore the association between glucose-lowering medications and severe hyponatremia.

DESIGN, SETTING, AND PARTICIPANTS

Subjects hospitalized with a principal diagnosis of hyponatremia (n = 14,359) were compared with matched controls (n = 57,383). Data were derived by linkage of national population-based registers. Multivariable logistic regression adjusting for co-medication, diseases, previous hospitalizations, and socioeconomic factors was used to explore the association between hospitalization for hyponatremia and the use of different glucose-lowering medications. Furthermore, newly initiated (≤90 days) and ongoing use was investigated separately.

MAIN OUTCOME MEASURES

Hospitalization due to hyponatremia.

RESULTS

The unadjusted ORs (95% CI) for hospitalization due to hyponatremia were 1.41 (1.29-1.54) for insulins, 1.38 (1.27-1.50) for metformin, and 1.22 (1.07-1.38) for sulfonylureas. However, after adjustment for confounding factors the association was consistently reversed. Thus, for any glucose-lowering medication the adjusted OR was 0.63 (0.58-0.68). For insulins, metformin and sulfonylureas, adjusted ORs (95% CI) were 0.58 (0.52-0.65), 0.81 (0.72-0.90) and 0.81 (0.69-0.94), respectively. Odds ratios for newly initated medications were overall higher while those for ongoing treatment were further decreased. Thus, adjusted ORs (95% CI) for ongoing treatment with insulins, metformin, and sulfonylureas were 0.54 (0.48-0.61), 0.82 (0.73-0.91) and 0.78 (0.66-0.92).

CONCLUSIONS

Glucose-lowering medications did not increase the risk for hospitalization due to severe hyponatremia. In fact, the association was inverse across all investigated drugs. The association may be mediated by pharmacologic mechanisms, but the uniform effects across drug-classes suggest properties of the diabetic disease are of importance.

Diabetes mellitus and electrolyte disorders

Diabetic patients frequently develop a constellation of electrolyte disorders. These disturbances are particularly common in decompensated diabetics, especially in the context of diabetic ketoacidosis or nonketotic hyperglycemic hyperosmolar syndrome. These patients are markedly potassium-, magnesium- and phosphate-depleted. Diabetes mellitus (DM) is linked to both hypo- and hyper-natremia reflecting the coexistence of hyperglycemia-related mechanisms, which tend to change serum sodium to opposite directions. The most important causal factor of chronic hyperkalemia in diabetic individuals is the syndrome of hyporeninemic hypoaldosteronism. Impaired renal function, potassium-sparing drugs, hypertonicity and insulin deficiency are also involved in the development of hyperkalemia. This article provides an overview of the electrolyte disturbances occurring in DM and describes the underlying mechanisms. This insight should pave the way for pathophysiology-directed therapy, thus contributing to the avoidance of the several deleterious effects associated with electrolyte disorders and their treatment.