I would like to know the side effects of the medicine triametrene/hydrochlorothiazide. Does it increase blood glucose and cause electrolyte imbalance?

Mainly potassium. Hydrochlothiazide can lower potassium and triamterene high potassium. Hctz (hydrochlorothiazide) can cause low sodium and high calcium. Most of the side effects should be on package insert with medication.
Yes and not ususally. Actually, if you have diabetes, it may have a very subtle effect increasing your blood sugar. If you don't have diabetes: no problem. Regarding electrolytes, the combination is designed to prevent electrolyte imbalance (hctz (hydrochlorothiazide) causes potassium loss, triamterene counteracts potassium loss and helps lower bp). It's a very old, very effective, very inexpensive drug combination used by many millions.
A good choice really. Triamterene/hydrochlorothiazide is an ideal fluid pill to use for treating high blood pressure because it is less likely to cause potassium imbalance. Hydrochlorothiazide alone depletes potassium, while triamterene conserves it. Hydrochlorothiazide may raise blood sugar levels slightly, though the benefits of good blood pressure generally outweight this disadvantage.
Medication. Potential to reduce potassium especially on a high salt diet. Can reduce magnesium. Can reduce sodium with high water intake. Can slightly increase glucose levels.