About 2% of all pregnancies are complicated by diabetes mellitus (DM), which either existed before the pregnancy or occurred during it. In either of these two cases, diabetes and pregnancy greatly complicate each other.
Over the years , White’s classification has been used in clinical practice , which is based on criteria such as the patient’s age when the first symptoms appear, the duration of the course of diabetes, and possible complications (for example, vascular diseases). In recent years, a simpler classification of the American Diabetes Association has been applied. This classification establishes three types of impaired glucose tolerance.
Type 1 diabetes first manifests itself in childhood, is characterized by instability of the course and difficulty of correction. It is believed that its cause is an autoimmune conflict that causes the destruction of pancreatic beta cells. With this type of disease, diabetic ketoacidosis (CKA) often develops. Type 2 diabetes occurs in adulthood. Such patients are usually obese and the therapeutic effect can be achieved by appropriate diet. The cause of this type of diabetes is more likely to be exhaustion than destruction of beta cells.
Gestational diabetes is a special type of impaired glucose tolerance that occurs only during pregnancy. In most cases, this condition is reversible, but in the future this category of women is a risk group for the development of diabetes.
The effect of pregnancy on diabetes.
During pregnancy , the diet often changes: the amount of food taken at the beginning of pregnancy is reduced, due to nausea, vomiting and a change in taste. Glucose metabolism is also significantly affected by pregnancy hormones. The most significant of these is the human placental lactogen (LPL), which is produced in excess by a growing placenta. NPL will affect both fatty acid metabolism and glucose metabolism. This hormone activates lipolysis by increasing the concentration of free fatty acids, reduces glucose uptake and gluconeogenesis, i.e. PPL is an insulin antagonist.
As the gestational age increases, the production of PPL increases and the effects it causes are amplified, which requires correction in the use of insulin. Other hormones, estrogens and progesterone, have less effect. They affect the interaction between insulin and glucose and the action of insulinase, an enzyme produced by the placenta and cleaving insulin. Such a versatile effect of pregnancy on glucose metabolism makes it difficult to correct concomitant diabetes. Pregnant women often develop diabetic ketoacidosis.
With an increase in renal blood flow , direct glomerular filtration of glucose also increases. At the same time, there is an increase in tubular reabsorption, but all the same, in the end, pregnant glucosuria occurs, an average of 300 mg per day. In diabetes, the glucosuria value may be even higher, but this indicator poorly reflects the level of glycemia and cannot serve as a guide for determining the real levels of glycemia. High-glucose urine is an excellent medium for bacterial growth, so urinary tract infections are twice as common in pregnant women with diabetes.
In addition to the difficulties associated with the treatment of diabetes , an increase in the incidence of DKA, pregnant hypertension and preeclampsia occur twice as often compared to pregnant women without associated diabetes. In 15% of patients, the course of diabetic retinopathy worsens during pregnancy.
It sometimes goes into a proliferative form , which further, without therapeutic laser coagulation, leads to loss of vision.