Inheritance of Diabetes. The risk of developing type 1 diabetes if either parent is afected is 3 to 5 percent. Type 2 diabetes has a much stronger genetic component. If both parents have type 2 diabetes, the risk of developing it approaches 40 percent. Both types of diabetes develop after a complex interplay between genetic predisposition and environmental factors.
Type 1 diabetes is prompted by environmental triggers such as infection, diet, or toxins and heralded by the appearance of islet cell autoantibodies in genetically vulnerable individuals (Pociot, 2016; Rewers, 2016). Some but not all studies have shown a reduction in risk for type 1 or type 2 diabetes associated with breastfeeding (Owen, 2006; Rewers, 2016).
Diabetes and pregnancy interact signiicantly such that maternal welfare can be seriously jeopardized. With the possible exception of diabetic retinopathy, however, the long-term course of diabetes is not afected by pregnancy.
In an analysis ofmore than 800,000 pregnancies, Jovanovic and colleagues (2015) found that 1125 mothers with type 1 diabetes were at increased risk for hypertension and respiratory complications compared with nondiabetic women. And, 10,126 mothers with type 2 diabetes had an elevated risk for depression, hypertension, infection, and cardiac or respiratory complications compared with pregnant controls. Maternal death is uncommon, but rates in women with diabetes are still higher than those in unafected gravidas. In one analysis of972 women with type 1 diabetes, the maternal mortality rate was 0.5 percent, and deaths resulted from diabetic ketoacidosis, hypoglycemia, hypertension, and infection (Leinonen, 2001).
Preeclampsia. Pregnancy-associated hypertension is the complication that most often forces preterm delivery in diabetic women. he incidence of chronic and gestational hypertension-and especially preeclampsia-is remarkably increased (Chap. 40, p. 713). In a systematic review and metaanalysis of 92 studies including more than 25 million pregnancies, Bartsch and associates (2016) calculated a pooled relative risk of 3.7 for preeclampsia in women with pregestational diabetes. In the study cited earlier by Yanit and colleagues (2012), preeclampsia developed three to four times more often in women with overt diabetes. Moreover, those diabetics with coexistent chronic hypertension were 12 times more likely to develop preeclampsia. As shown in Figure 57-5, women with type 1 diabetes in more advanced White classes of overt diabetes, who typically exhibit vascular complications and have preexisting nephropathy, are more likely to develop preeclampsia. This .g:-.
.E )
FIGURE 57-5 Incidence of preeclampsia in 491 type 1 diabetic women in Sweden and the United States. (Data from Hansona, 1993; Sibaib, 2000.) rising risk with duration ofdiabetes may be related to oxidative stress, which plays a key role in the pathogenesis of diabetic complications and preeclampsia. With this in mind, the Diabetes and Preeclampsia Intervention Trial (DAPIT) randomly assigned 762 women with type 1 diabetes to antioxidant vitamin C and E supplementation or placebo in the irst half of pregnancy (McCance, 2010). Preeclampsia rates did not difer except in a few women with a low antioxidantstatus at baseline.
Diabetic Nephropathy. Diabetes is the leading cause of end stage renal disease in the United States (Chap. 53, p. 1034).