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Understanding gestational diabetes mellitus

Feb. 17, 2015
Gestational diabetes mellitus (GDM) occurs in approximately 7% of pregnancies, and can cause significant lifelong complications for both mother and child. As inflammation throughout the entire body increases the risk of diabetes, oral health professionals should be aware of this disease and its association with periodontitis.
Gestational diabetes mellitus (GDM) is defined as any degree of glucose intolerance with onset or first recognition during pregnancy. (1) As the fetus develops, the placenta produces several hormones that can block insulin and lead to insulin resistance, causing more sugar in stay in the blood. Approximately 7% of all pregnancies are complicated by GDM, resulting in more than 200,000 cases annually. (2) Risk factors include marked obesity, personal history of GDM, glycosuria (i.e., glucose in the urine), or a strong family history of diabetes.

A fasting plasma glucose level 126 mg/dl (7.0 mmol/l) or a casual plasma glucose 200 mg/dl (11.1 mmol/l) meets the threshold for a diabetes diagnosis if confirmed on a subsequent day, and precludes the need for any glucose challenge. (2) A casual plasma glucose test is taken at any time of day regardless of the time of last meal. There are numerous obstetric and perinatal concerns, such as increased frequency of maternal hypertensive disorders, the need for cesarean delivery, and an increase in the risk of intrauterine fetal death during the last 4–8 weeks of gestation. (2)

ADDITIONAL READING |Diabetes: A new toolkit

Long-term, women with GDM are at greater risk for the development of diabetes, usually type 2, after pregnancy. Obesity and other issues that encourage insulin resistance increase the risk of type 2 diabetes after developing GDM; markers of islet cell-directed autoimmunity are associated with an increase in the risk of type 1 diabetes. (2) Children of women with GDM are at increased risk of obesity, glucose intolerance, and diabetes in late adolescence and young adulthood. Monitoring and management is important to keep serum glucose levels under control.

Access the pamphlet by clicking this image.

There is a wonderful pamphlet on this topic available from the CDC (see right). It is filled with information about planning pregnancy and controlling diabetes. It outlines how uncontrolled diabetes can harm the fetus, and possibly cause preeclampsia in the mother. There are helpful charts for patients to keep their own records. It is also available in Spanish.

Some cross-sectional or case-control studies have shown that clinical periodontal disease has been associated with gestational diabetes mellitus. (3) Another small study measured clinical and other periodontal-disease-related parameters at least 7 weeks prior to the diagnosis of GDM. (4) Women with GDM had higher C-reactive protein, TNF-, and IL-6 levels, though only the C-reactive protein levels were statistically significant. Also, clinical measures of periodontitis in the GDM group were higher, though not significant, due to study limitation (e.g., small size). The authors speculate that periodontal disease-induced inflammatory mediators could exacerbate insulin resistance, possibly intensify the preexisting pregnancy-induced insulin resistance, and further impair glucose tolerance.

ADDITIONAL READING | Screening for diabetes in the dental office

Our role is to help prevent complications of dental and oral diseases during pregnancy. We want to integrate oral health care into overall health care, and refer and communicate with other health care providers as necessary. Remember that any inflammatory process, including acute and chronic periodontal infection, can make diabetes control more difficult and is associated with adverse pregnancy outcomes. Thorough self and professional care to avoid or minimize dental infection is important for pregnant women with diabetes. Controlling all sources of acute or chronic inflammation helps control diabetes.

1. Proceedings of the 4th international workshop-conference on gestational diabetes mellitus. Diabetes Care. 1998;21(suppl 2):B1-167.
2. The American Diabetes Association. Gestational diabetes mellitus. Diabetes Care. 2003;26(suppl 1):S103-5.
3. Novak KF, Taylor GW, Dawson DR, Ferguson JE 2nd, Novak MJ. Periodontitis and gestational diabetes mellitus: exploring the link in NHANES III. J Public Health Dent. 2006;66:163-8.
4. Dasanayake AP, Chhun N, Tanner ACR, et al. Periodontal pathogens and gestational diabetes mellitus. J Dent Res. 2008;87:328-333.

Maria Perno Goldie, RDH, MS, is the editorial director of RDH eVillage FOCUS.