Why are diabetic people often overweight? I was looking at diabetes the other day, and I noticed something strange. Lower amounts of lipase are a symptom of diabetes, as is overweightness. However, since lipase is the enzyme that breaks down fats, shouldn't a lack of it mean that less of it enters your blood stream and is simply excreted instead? In that case, how come diabetic people are often overweight? This question has been bugging me for ages, does anyone know why?

How are diabetes and obesity connected in light of low lipase activity?
Short answer: There's more than one type of diabetes. (And to complicate things, there's also more than one type of lipase. It's unclear from the question which type were mentioned in what you read.)

_Diabetes mellitus_ is usually divided into Type 1 (insulin-deficient) and Type 2 (insulin-resistant). Obesity is a risk factor for Type 2 diabetes, but not all diabetics are overweight. In fact, people with Type 1 are often lean.

Decreased lipase activity is not a major symptom of diabetes. However, these two articles suggest that plasma lipase activity may be lower in cases of Type 1 diabetes but not Type 2.
Junglee, D. et al., Low pancreatic lipase in insulin-dependent diabetics, 1983.
Dendona, P. et al., Exocrine pancreatic function in diabetes mellitus, 1984.