I am very scared. I have a family history of GESTATIONAL diabetes (there were only two people in the family with type 2 diabetes–my grandparents’ brother/sister). I am 25 years old. I was about 10 to 15 pounds overweight pre-pregnancy.

I gained a lot of weight quickly with this pregnancy, about 30 pounds by 20 weeks. I was tested early, around 21 or 22 weeks, for gestational diabetes because of the family history. I didn’t do the glucose tolerance test. I had a random blood test done and my numbers came back “slightly elevated.” I was put on a special diet. I NEVER had a normal fasting blood sugar, so I knew I’d be on insulin for that. My post meal blood sugars were fine, slightly high, but under my goal. Three weeks later, at my next doctor’s appointment, my after meal blood sugars were high (even though I was eating the same thing) so I was put on insulin four times per day.

I have my after meal blood sugars under control with 10 to 15 units three times a day. My fasting blood sugars, on the other hand, are still out of control, from 90 mg/dl [5.0 mmol/L] to 133 mg/dl [7.4 mmol/L], with 126 mg/dl [7.0 mmol/L] on a few occasions. I’m now on 40 units of insulin at night and only had ONE normal fasting blood sugar, which was 78 mg/dl [4.3 mmol/L]. I talked to my obstetrician today and she terrified me. She said because I’m having such a hard time with my fasting blood sugars that I may have had pre-existing diabetes. Does this seem right?

I am upset because they never gave me an A1c test, which could’ve helped me figure out if I had it before. Now, I fear it’s too late for that test since I’ve already been diagnosed for over 45 days and it may not be accurate.

Also, another thing that was weird to me was one night I took 42 units of long lasting insulin and my blood sugar was 78 mg/dl [4.3 mmol/L]. The next day I took 42 units and my blood sugar was 105 mg/dl [5.8 mmol/L]. The following night, I took no insulin and my blood sugar was 99 mg/dl [5.5 mmol/L]. What is going on with that? No one can seem to give me an answer.

Determining whether you have preexisting diabetes or not will have to wait until after you deliver. In the meantime, it is a matter of adjusting your insulin. I recommend that you check your blood glucose just before and one hour after each meal. The parameters that I use are as follows: fasting 70 mg/dl [3.9 mmol/L] to 90 mg/dl [5.0 mmol/L], just prior to a meal; less than 100 mg/dl [5.6 mmol/L] one hour after a meal; and less than 130 mg/dl [7.2 mmol/L]. Glucose control can be challenging, not so much because of preexisting diabetes, but more due to the degree of insulin resistance that is occurring due to the pregnancy. Insulin resistance increases as the pregnancy progresses, necessitating higher doses of insulin. This is expected, so do not be discouraged. Women with gestational diabetes can often be on large amounts of insulin (over 100 units/day). Sometimes it requires more than two injections each day. These adjustments can be made by your doctor based in your pattern of blood glucose values. You will not have perfect values every time, but do your best. I have no explanation why you had a normal fasting despite no insulin the night before although it may reflect what you ate that evening (i.e., a low carbohydrate meal).

OWJ
Additional comments from Dr. Jim Lane:

The diagnosis of diabetes should be made on hard endpoints. The only way to have known if you had previous diabetes is to have had fasting glucose levels that can be evaluated. Although you did not have a formal oral glucose tolerance test, it sounds like your fasting glucose numbers were high enough to make the diagnosis. Note that the cause of underlying gestational diabetes is the increasing insulin resistance in a genetically susceptible individual. The placenta makes hormones that antagonize insulin’s effects. The amount of hormone increases over time and the degree of glucose intolerance may become more severe. I am not sure your obstetrician can make the diagnosis that you had previously undiagnosed diabetes prior to pregnancy based on difficulty of control. She can be thinking out loud and saying to you and herself whether it is possible. That is always a reasonable point and remains an unanswered question if you do not have pre-pregnancy glucose values to evaluate.

The nighttime NPH helps to suppress the output of glucose from your liver. Normally, there is a given amount of glucose that comes from the liver to keep the brain supplied with this obligate source of fuel. However, in diabetes, one of the metabolic abnormalities that occurs is too much glucose being put out. The strategic location of NPH administration at bedtime is to keep the glucose output overnight decreased enough for you to have normal fasting glucose levels. The reason you had a less than high glucose level after you did not have an injection the night before is not uncommon. You still have some NPH around to keep from escaping totally from its effects. A few more nights of avoidance of insulin would have allowed the glucose to have gone much higher. Keep working with your doctor to achieve those target blood sugars. It is similar to a sprint during pregnancy.

After delivery, you will need to have an oral glucose tolerance test to see if your diabetes has gone away or whether it persists. Note that patients who have gestational diabetes have a very high rate of diabetes at a later date. This will require you to have close medical follow-up and you will also need attention to a healthy lifestyle.

JTL