Which of the following can cause hypomagnesemia?

Hypomagnesemia, which is a low level of magnesium in the blood, can be associated with a prolonged QT interval on an electrocardiogram. This is due to magnesium's critical role in cardiovascular health, particularly in the maintenance of normal cardiac rhythm. Magnesium acts as a natural calcium blocker, and low levels can lead to disturbances in cardiac conduction, which may manifest as a prolonged QT interval. This condition can increase the risk of arrhythmias, particularly torsades de pointes, which is directly linked to magnesium deficiency.

The other conditions listed, such as hypertension, hyperlipidemia, and diabetes mellitus, are not directly associated with causing hypomagnesemia. While they can affect overall metabolic and electrolyte balance, they do not specifically result in low magnesium levels in the same way that prolonged QT interval is affected.