Obesity is strongly linked to the development of type 2 diabetes. It is also associated with other diabetic conditions and complications, including:

• Prediabetes. A condition in which glucose (blood sugar) levels are higher than normal, but not high enough for a diagnosis of diabetes. According to the American Diabetes Association, 54 million Americans have prediabetes. Insulin resistance is a closely related state. Recent research shows that some people with prediabetes have complications that were once associated with diabetes, including cardiovascular damage and nerve disease (diabetic neuropathy).
  
  For more than half of the people with prediabetes, healthier eating, increasing exercise and moderate weight loss could mean delaying the development of diabetes or preventing it altogether. For example, a 200-pound man who loses just 5 percent of his body weight (10 pounds) may drop his glucose level down below prediabetic levels.
  
  
• Hyperinsulinemia. An excess of insulin in the blood. Hyperinsulinemia can lead to complications including hypoglycemia (low blood sugar), excessive blood clotting, cardiovascular disease, kidney stones and gout.
  
  
• Gestational diabetes. A temporary form of diabetes that can develop only among pregnant women. Women who have gestational diabetes also have a greater risk of developing type 2 diabetes later in life. Obesity also increases the risk of pregnancy complications such as preeclampsia.
  
  
• Type 1 diabetes. An autoimmune condition in which the pancreas stops producing insulin. Many people with type 1 diabetes are of normal weight or even underweight. However, excess weight in those predisposed to type 1 diabetes may cause the disease to develop earlier in life. In addition, people with type 1 diabetes who become overweight or obese can develop insulin resistance, a condition known as double diabetes.

• Cardiovascular disorders. These are the primary cause of death in people with diabetes. Obesity is linked to dyslipidemia (unhealthy levels of cholesterol and other blood fats), blood vessel diseases (e.g., diabetic angiopathy, atherosclerosis), elevated blood pressure, heart conditions, stroke and metabolic syndrome.

• Kidney conditions. Overweight and obesity increase the risk of proteinuria, diabetic nephropathy and end-stage renal disease.
  
  
• Eye diseases. Obesity and two conditions that often accompany it, high blood pressure and unhealthy cholesterol levels, may accelerate diabetic retinopathy. High blood pressure is also linked to increased risk of cataracts and glaucoma.
  
  
• Cancer risk. Obesity is believed to account for part of the reason diabetes increases the risk of several cancers.
  
  
• Acanthosis nigricans. This skin condition may appear in overweight people who are insulin resistant.
  
  
• Polycystic ovarian syndrome (PCOS). This hormonal imbalance in women is linked to insulin resistance and type 2 diabetes.

Obesity also increases the risk of many other conditions, including arthritis, back pain, respiratory problems, sleep apnea, nonalcoholic fatty liver disease, gallbladder disease and prostate enlargement (benign prostatic hyperplasia).

Obesity often reflects poor dietary habits and a sedentary lifestyle, both of which can lead to unhealthy fluctuations in glucose (blood sugar). Conversely, people with diabetes who are able to lose even modest amounts of weight can see dramatic decreases in their risk for developing complications and increase their ability to control glucose.