The term DIABETES actually means "excessive urination". When that excessive urination is caused by having blood sugars too high, then the term is DIABETES MELLITUS. There is another form of Diabetes called DIABETES INSIPIDOUS, where the excessive urination is NOT caused by high blood sugar. Diabetes Insipidus is less common that Diabetes Mellitus. For Diabetes Mellitus, there are several sub-types. The obvious are Type 1 (where the pancreas has failed, and the patient MUST have insulin injections) and Type 2 (where the pancreas is working, but cannot produce ENOUGH insulin. This is usually because the patient is overweight.). Lesser known are Gestational Diabetes (the patient is pregnant) and Traumatic Diabetes (where the patient has some form of injury, often a head or brain injury). As for your question, an UNTREATED Diabetic WILL NOT HAVE LOW BLOOD SUGAR. The LOW blood sugar comes in when the patient begins treatment. Type 2 Diabetes is most often treated with diet and exercise. The idea is to get the patient to lose weight. When the patient gets down to a "normal" weight, the blood sugars WILL come under control, and no medications are needed. But many patients are stubborn and refuse to change their lifestyle, and there are several different Diabetic Medications that help lower blood sugar. When these are taken ALONG WITH DIET AND EXERCISE, the patient has the possibility of having a HYPOGLYCEMIC ATTACK. Low calorie diet, plus increased exercise, plus additional medications will often result in the patient having SEVERELY low blood sugars. When this happens, the patient needs to call their doctor, who may be able to recommend a lower dosage of medication or possibly a slightly higher calorie diet. "It's rare that I hear about diabetes being diagnosed from having low blood sugar." Uhhh . . . no. It is IMPOSSIBLE to diagnose Diabetes from LOW blood sugar, because Diabetes is defined as having consistently (almost all the time every day)HIGH blood sugar. But there is a problem called HYPOGLYCEMIA, which is the OPPOSITE of Diabetes . This is when the patient's blood sugar is consistently TOO LOW. This CAN have medical causes, but the most common cause is POOR DIET. Hypoglycemia is often found in supermodels and silly teenage girls who want to think they look like supermodels. These people eat far too FEW calories, the blood sugar becomes low, and they literally "run out of fuel". Blood Sugar is the FUEL your body needs to work, grow, and heal. When you have too low blood sugar, YOU FAINT. Hypoglycemia is actually much more immediately serious that Diabetes . Imagine what happens if you faint from hypoglycemia while driving 65 MPH on the interstate! The cure for Hypoglycemia is usually simple: EAT SOMETHING. The same goes for the diabetic that is under treatment. Knowing the POSSIBILITY of a hypoglycemic attack, most diabetics will keep something like hard candies or special Glucose Tablets in their briefcase or purse or pocket "just in case". BTW: There are no "degrees" of Diabetes , any more than there are "degrees" of being pregnant. Either you are, or you are not. Yes, if your blood sugar is CONSISTENTLY (most of the time every day) more than 150, the YOU ARE DIABETIC. There is no "a little bit diabetic", and there is no "pre-diabetes". Either you have it, or you do not. Either you need treatment, or you do not.