I don't know whether insulin injections would be the best course of action for you, my young friend, as that decision MUST rest with your gynae [gyne, if you prefer the American spelling) team.
What I can tell you though is that your blood sugar (glucose) levels ARE too high. Higher than 'normal' blood sugar levels can be very damaging to both yourself and your baby.
The safest method of lowering your blood sugar levels, if you're not able to do it with exercise and diet control, is by taking insulin. There aren't the same sort of side-effects that could affect your baby if tablets were used.
Hopefully, your doctor will make a referral for you to see a dietitian who would be able to advise you on the types of foods and drinks that are raising your blood sugar levels so much, and which ones would be better for you to use instead.
Congratulations, by the way, on your pregnancy. I truly do hope that your pregnancy continues as planned and that neither the pregnancy or the delivery are too uncomfortable for you.