Coffee can lower risk type 2 diabetes mellitus

Several large prospective studies have reported an inverse association between coffee consumption and risk of type 2 diabetes mellitus. High coffee consumption has been associated with better glucose tolerance and substantially lower risk of type 2 diabetes mellitus in diverse populations in Europe, U.S., and Japan. The inverse associations between coffee intake and diabetes risk were stronger for decaffeinated coffee than for regular (caffeinated) coffee.

The major diterpenes in coffee are cafestol and kahweol, which make up approximately 1% (wt:wt) of coffee beans. Both cafestol and kahweol increase insulin secretion and glucose uptake in muscle cells.

Cafestol is universally present in Coffea species. Researchers have found that cafestol – a bioactive compound present in coffee – increased insulin secretion, reduced fasting glucose levels, and improved insulin sensitivity in mice.

Previous studies have shown that moderate coffee consumption may prevent the development of type 2 diabetes mellitus and confirmed that caffeic acid and chlorogenic acid have the potential to decrease the risk of type 2 diabetes mellitus.

The differentiation between filtered and boiled coffee may be relevant for risk of type 2 diabetes mellitus. It was observed that for the same amount of coffee, risk was lower for people who consumed filtered coffee.
Coffee can lower risk type 2 diabetes mellitus 

Cafestol and kahweol in coffee

Cafestol and kahweol are fat soluble compounds knows as diterpenes, which have been found to raise serum lipid levels (causing a rise in total cholesterol, low-density-lipoprotein (LDL) cholesterol, and triglycerides) and affect liver.

The structure of cafestol and kahweol is nearly identical, differing in only in the degree of saturation of one conjugated bond to the furan ring.

The diterpenes occur largely as fatty acids esters, esterified at the primary hydroxyl group.  Some cafestol and kahweol are extracted from ground coffee during brewing, but are largely removed from coffee by paper filters.

Diterpenes exhibit good stability at high temperatures, but they can form dehydro-derivative (dehydro-cafestol and dehydro-kahweol) in small amounts when roasting temperatures are raised.

Because coffee beans are high in cafestol and kahweol, ingestion of coffee beans or grounds on regular basis may also raise serum and LDL cholesterol.

Scandinavian-style boiled coffee and Turkish-style coffee contained the highest amounts, equivalent to 7.2 and 5.3 mg cafestol per cup and 7.2 and 5.4 mg kahweol per cup, respectively.
Cafestol and kahweol in coffee