Is either of them a sex linked disease? Can either one be inherited? My book says, "this disease is transmitted as a recessive genetic characteristic." What does this mean?
Neither are sex-linked. Type 1 can be directly inherited (in a non-Mendelian fashion), but Type 2 genetic factors mostly increase risks. "Recessive genetic traits" are traits that only express themselves when ONLY the recessive alleles are present in the organism (a dominant allele, if present, will 'overpower' recessive one).
Diabetes mellitus Type 1 (Juvenile Diabetes) is inherited, but it is autosomal with complex dominant/recessive rules:
Type 1 diabetes is a polygenic disease, meaning many different genes contribute to its onset. Depending on locus or combination of loci, it can be dominant, recessive, or somewhere in between.
That results in some interesting, albeit complex, expressions:
The risk of a child developing type 1 diabetes is about 10% if the father has it, about 10% if a sibling has it, about 4% if the mother has type 1 diabetes and was aged 25 or younger when the child was born, and about 1% if the mother was over 25 years old when the child was born.
Diabetes mellitus Type 2 does have genetic components, but the vast majority merely increase the risk of developing Type 2 Diabetes. Environmental factors play a large role in Type 2.
Excess body fat is associated with 30% of cases in those of Chinese and Japanese descent, 60-80% of cases in those of European and African descent, and 100% of Pima Indians and Pacific Islanders.